They, especially Rusedski, have been banging on about the 'changing of the guard' for a few years now.
None of the current top 20 show signs (so far) of being as good as the top 4 were/are when they're fit and healthy, imo.
There's a few players (2 or 3 Italians especially) outside of the top 20 that look like they might be up to it, so we'll just have to wait and see.
I don't see any Brits coming through yet, unfortunately.
ETA: I'm looking forward to seeing what Murray/Soares can achieve next year in the men's doubles. I had a feeling Murray/Skupski would be splitting up as the energy and positive attitude just wasn't there in the last few tournaments of the year. You could tell Murray just wasn't happy and that he felt he needed to win more than his fair share of the points. I wonder who Neal Skupski is going to partner, haven't seen anything on that yet. Salisbury/Ram must be gutted losing their (London) semi-final the way they did, so close, they must have thought they had it. It was frustrating to watch too, tbh.