There have been formulas in the past for overachieving with squads of limited potential. Some managers have been capable of it, some haven't.
It amazes me that Palace were as low as they have been, with some great talent in the side. Remember, Roy Hodgson got Switzerland up to be ranked number 3 in the world. Greece got into the final at Euro 2004. Look at some FA Cup winners back from Wigan back through Wimbledon, Coventry, West Ham, Southampton, Sunderland etc.
It's fair to say Rafa has done an amazing job with minimal backing.
What could have been a totally crap season is coming to a close. There may or may not be opportunities over the summer, whether it is new ownership or Ashley finally seeing the light.
Now is the time to wait and see what happens. Rafa has shown himself to have been totally able. If he stays, I hope he is supported by Ashley. If he is not supported, I hope he leaves. he has at least given the club a chance to match his ambitions. If the club don't respond in kind, anyone who chooses to financially support Ashley will get what they deserve.