We don't really have much of a choice but to be patient I'm afraid. Nothing we can do will help Ivy find a new mate if Princess doesn't return.
Is it too late for Princess to return? No, but every additional day decreases the chances.
Is it too late for Ivy to find a new mate? No, far from it.
Do we know that Ivy hasn't already found a new lady friend (Joli or someone else)? No.
Is it too late to have chicks at the Radisson? No, we've had birds raise young start much later than this. Having said that, it's always a possibility - we've had chickless years before, only a couple.
Ivy doesn't seem to want to give up the Radisson which is a good thing, the Hotel is a magnet for birds, so if Princess doesn't return, a female passing through town will easily hit the Radisson and not meeting a defending female, could easily take over the territory. Or its possible that the courting is done and we are now just waiting for Joli to lay eggs.
Nothing like a little excitement to start out the year ...