I'm on the fence, but leaning more towards giving Sage more time and support.
That is not because I have any strong reason to believe in Sage, though. It's because sacking the manager must always be the last resort when other options have been exhausted. Club stability is key, as is a clear and consistent message to the players, their agents, and the media that the board, Parish, Hobbs and the coach are all together as one, and that the players can't separate them and play one off against the other if they happen to dislike a particular manager. We see that so often at other clubs. Player power, sulking, division then, inevitably, collapse. No thanks.
I'd give Sage more time, but expect him to do things differently. His methods are poorly suited to the circumstances (which are not of his making) if they are even capable of working at all. That doesn't necessarily mean he has to tear up every single thing he believes in. I remain torn between (on one hand) knowing that we've never, ever seen a front-foot, attack minded Palace team do well in the premier league and (on the other hand) seeing other teams like Bournemouth do it.
I'm not against a more front-foot manager. If the end result of all this is that Palace win and lose games 3-2 instead of 1-0 on the way to finishing 12th again, then I'm fine with that. That is absolutely not what is happening, though. We have failed to score in more than half of our league games. There is no single part of the current approach that seems promising.
Regarding Sage's almost religious faith in the 343 system, I actually don't mind a bit of tactical inflexibility. To me, there is as much to be said for consistency and clarity as there is for flexibility and adaptability. If he had changed between systems in his games so far, we would all be moaning that he doesn't know his best team and formation, and should nail one down and given it a chance to work. In this case, though, Sage really does have to go back to the drawing board.
As to what Parish may do: Going back, I thought Pardew was very unlucky to be sacked (to the point it seemed unjust), and had similar feelings when Vieira got the bullet. They both had loads more time than Sage, of course, and form and results had tailed off, but I just felt both managers had shown enough previously to assure me they would fix it. They had both been able to put together viable premier league Palace teams for sustained periods. Sage doesn't have that credit in the bank. I don't know that he can produce a stable team at Palace, and what little evidence there is doesn't go in his favour.
At least give him the chance to change, though.