I disagree with the ones saying 35+ are just as capable, knowledge-wise sure. Reflex wise, not at all. I've done some e-sports in other games and the differences may on a grand scale be very small, but that very small amount at the top .01% is actually pretty extreme, the difference between basically top .01% and top .03% which again may not seem like a lot is a HUGE gap. The only ones that can keep up with that gap at all are ones that are already into it and don't stop, if you stop for even a short time, you aren't getting it back.
That said, I don't really see the value of a 35+ league. Hopefully, clash will FINALLY become a full release, and that will do nicely IMO.