well since tatsuki won two GPs last season and was second at nationals and fifth at the olympics and missed out on a world title by less than half a point i'd say there's a good chance he's going to be one of the top skaters in japan (and the world) in the next few years, if he stays healthy.

and taka(hiko) isn't retiring yet. idk how much longer he'll stay and he's had trouble with injuries but i wouldn't count him out yet. i doubt he'll win any more major titles at this point, much as i'd like him to, but i think he can still be a medal contender on the international stage even though he gets lowballed in PCS all the time.

takahito (mura) has potential because he has nice jumps when he lands them but he needs to be more consistent or he'll never get higher PCS from the judges. but yeah, these three are probably going to be the top japanese guys along with yuzuru next season.

the juniors...i don't think the juniors will be a threat anytime soon. then again, it's hard to tell with juniors. keiji tanaka and ryuju hino are turning senior next season. i like keiji but he's really inconsistent and desperately needs to fix his spins. (still, tatsuki was a hot mess for years before he finally got it together, so maybe there's hope for keiji yet.) ryuju gets like 0 PCS from the judges and also i don't really like his skating and had a rough time last season. i love shoma the most but his jump technique is probably going to get him nowhere. all the other juniors with potential are much younger, like 13 or 14, and it's a bit too soon to say much about them, and it'll be some time before they rise to prominence, probably.