Concerns about Silva's form are obviously legitimate. Aside from the first five games or so, he's not been anywhere near as brilliant as he has in previous seasons, and at times actually pretty poor by anyone's standards.
I'm far from convinced that it's a sign of terminal decline though. There are plenty of factors that might be cited in mitigation - his injuries, those of De Bruyne and Nasri that have meant that he's had to carry the creative burden pretty much single-handedly for most of the season (and, as such, be overplayed), the fact that the entire team has, by and large, been fairly shit since September etc.
I also think the extent of his struggles are being a bit overegged in some quarters - the PSG game being a classic example. I thought he was poor for the first 15-20 minutes, during which he gave the ball away cheaply on 3 or 4 occasions. There were also a couple of moments over the 90 minutes where his defending left a bit to be desired, to say the least (the 'offside' attempt being the most glaring!). But then he clearly wasn't under instruction to play the role as if he were Sterling - i.e. to hold his position out wide, to double up with Clichy at all times etc. Rather he was given license to move inside and get on the ball - with Fernando and Fernandinho briefed to get across quickly and cover that space, and Clichy told to get as tight as possible to the wideman to stop them building up 2 on 1 situations. And I reckon that worked in both regards: Fernando, Fernandinho and Clichy were all excellent, and Silva was able to get on the ball in central areas and give us some measure of control - he was the one always in space to receive the ball, he knitted pretty much everything together that we did going forward, and he also brought De Bruyne into the game (some of the play between the two of them was outstanding, and had as much to do with Silva as De Bruyne, in my opinion). I don't know what the possession stats were - perhaps about 35%-65%? Had Silva not been playing, and say Sterling had been in instead, there's a good chance that figure may have dropped to around 25% - whether that would have made huge difference, who knows? Would we have held out defensively if they had more of the ball? Would De Bruyne have been so effective if we had less of the ball? Difficult to say, I would have thought. But I do think Silva made a positive contribution that has, perhaps unfairly, been overlooked.
As to what happens over the summer, again who knows? It could that Guardiola decides to move on with someone else. Or it could be that the medical staff give him the nod that they think the injury won't heal and is going to continue to hamper him. Personally though, I suspect that Guardiola will be looking forward to working with him, and that he'll probably thrive - and that this season's problems will come to be seen as just a blip in his time with us.