I have stuck in my two penneth worth on this subject in the past, speaking as one who works in the world of planning and is also something of a stadium geek.
For me, the idea of a new main stand roughly as tall as the holmesdale was the only show in town as soon as uncle Ron built the latter in the mid 90s; To have a ground where the biggest stand is behind the goal and everything else is half the height is every bit as mad as stopping the game to watch a video, or playing a world cup in the winter; It goes against the established norm. On a similar point, the new main stand will be an architectural oddity if the other two stands remain half it's height.
Anyway, my own view has always been that it may be possible to redevelop selhurst into a good, traditional, 40,000-plus ground akin to villa park, at least so far as planning regulations and physical space are concerned.
The main stand has approval. In fact, it got approved in record time and, as we all know, requires the demolition of nearby council houses. This is not an arrangement that most councils would accept. The idea that Croydon council don't want to help the club is palpably wrong. It's not up to the council to find us land for a stadium, or to build anything for us. Their job is to say yay or nay to whatever the club proposes, and they said yay. Quickly. Requiring replacement houses and some minor improvements to the area is the very least they are due, and they'd be negligent if they didn't insist on them. That's just how the system works. Development is indirectly taxed. Furthermore, reading between the lines of several things Parish has said on the matter, it seems clear that the council may well be prepared to use compulsory purchase powers to buy the Sainsbury's ransom strip if an impasse lingers. It's far quicker to just agree a deal, but the council wants the investment in the area and that's exactly what CPO powers are for. I see no reason to view them as anything other than on the clubs side, insofar as sides can be taken. Fair play to Parish, perhaps he wants to build a working relationship with Sainsbury's and that's why we haven't had to go down the CPO route, but I strongly suspect the council has the club's back on that issue.
So, odds and sods aside, the main stand can go ahead. The holmesdale exists. Sometimes I wonder how. It's height relative to the houses opposite is not something you would bank on being approved again. Doesn't matter now, it's there. It doesn't set a precedent though, as the decision to approve is so old that we couldn't rely on it if trying to build a similar building in place of the Arthur, which faces out onto houses over a similar distance.
The biggest issue regarding the Arthur, however, is that the current stand holds some 9500 people. For context, the new main stand would replace one holding 5500 with one holding 13500, a massive uplift in capacity. The same is not true of the Arthur, as it's so big already. Even if the club rebuild the Arthur in a mirror image of the new main stand, they won't get anything like the same capacity increase, and that's without considering that all the executive facilities would be harder to accommodate in the Arthur, as there isn't the car park etc there to facilitate it. It wouldn't pay for itself anything like as quickly, if at all.
Furthermore, there are a lot of houses along park road which may have their light and outlook harmed by a new, tall, Arthur. As has been pointed out, the houses on park road are (we presume) privately owned rather than council owned, so the idea of buying them just to knock them down requires either careful buying up over time and/or the council to CPO them. Liverpool did this. In our case, I can't see it. We are not as rich a club as Liverpool and the houses are worth a lot more. Moreover, the lack of housing in London is such that we would have to provide replacements elsewhere. That's been hard enough with six houses in the main stand project, so Christ knows how palace would manage it for three or four times as many on park road. Personally, I think a refurbished Arthur would be the way to go.
The Whitehorse is interesting. If we had bottomless pockets we could perhaps look at building a similar stand there to the holmesdale and providing Sainsbury's with a new, replacement store underneath as part of it, as the stand and the supermarket make a big enough plot between them for such a development. I'm pretty sure the houses facing Whitehorse lane don't have rear windows, so it's not quite as constrained as it might seem. The uplift in capacity from such a project would be huge (around 6000 more). I sometimes wonder if Parish has all this in mind when negotiating with Sainsbury's over the main stand ransom strip; They may hold a good few cards in the longer term.
So, 8500 in the holmesdale. 13500 in the new main stand. 9500 in the Arthur at present. If the Whitehorse can be made into 8500 too, we are getting to 39000, then fill in the corners.
To return the overall architectural incompleteness a single-tier Arthur would result in, I'd turn my attention to various clever schemes to squeeze executive boxes or a small upper tier over the top, perhaps mid-way towards the pitch, or even just a roof at a steeper pitch to meet the roofs of the holmesdale and a new Whitehorse. That wouldn't block light or views to houses on park road, and would join up the ground neatly.
Ultimately, if the Whitehorse stand redevelopment was made possible, everything else falls into place. Basically, one stand exists (holmesdale), one has been approved (main), so if the Whitehorse is possible it makes sense to compromise a bit on the Arthur. In idle moments I even wonder about a new, continuous roof flowing from the main stand out over the holmesdale and new Whitehorse, down over the Arthur. It could look good. A little unusual perhaps, but good.
Of course, the elephant in the room is funding. Textor was quite vocal about how much he helped with the costs of the academy (fair enough) and the Americans have helped out with a few loans here and there. FFP (which is real, by the way) prevents them splurging on players, but not on bricks and mortar. I wonder what they are there for if not to invest in redevelopment, and the club have welcomed them in, yet the main stand project drags on. Why is not clear. If it paid for itself in a reasonable period, surely that's exactly where an outside investor would put their dough? Ultimately, if the sums aren't attractive then the rest falls away. For me, that's where the real issue is.