They aren't that good, which is why I think they might stay. There are no Eichel's here.
There are a number of considerations that go into the decisions, so it might not be as simple as if they are NHL ready or not, but Beecher is more of a 3 year college player, in my opinion. He'd need a big improvement in his second year than most expect to be good enough to leave after 2. York, I think it's 50/50. I think he's closer to being able to leave than Beecher. The Flyers don't exactly need him on their blue line yet, so that might help the argument for him to stay. Power, he'll probably be a top 3 pick, but how often do defensemen go straight to the NHL after being drafted? It's not often. Most of the time, the first defensemen picked does not play in the NHL the next season. How much does he gain on the average first defensemen picked with his skillset and that he's one of the older first year draft-eligibles for 2021?
The rest, I don't see any of them being NHL players next year. I guess its possible for someone like Hughes, Beniers, Johnson, and Samoskevich, but I think the they'd need to hit a 95-100% outcome for their season and development this year for that to happen. It seems a little too unlikely to happen, in my opinion.