"Architect who doesn't code" is a terrible thing. I've designed projects and then turned them over to other skilled developers more than once, while I help them out with reviews and such. My knowledge is noticeably rusty in under a month and by month three I'm easily wrong at least as often as I'm right about what some other bit of code is doing. To even help them out on occasion requires a bit of re-orientation; I can't imagine trying to hand them fresh architecture requirements.

In fact, I've noticed it's kind of concerning when this doesn't happen; it means the engineers who took it over lack the confidence for some reason to make non-trivial changes to the code base and are just pecking at the sides. Unless the project is deliberately in maintenance mode, that's a problem. Could be people, could be me, could be them, could be technical issues, could be lots of things, but there's certainly some sort of problem there.