My 2 cents.
ebikes: I can’t see this being a thing for comp style trials, maybe better suited to oldschool hill climbs but the extra weight would hinder the size of moves more than the advantage of extra power would help them in my opinion.
disc brakes: never gonna happen for 26” comp trials, the extra weight, exposed fragile disc and spoke flex are way more of a handicap than the occasional rim grind.
geo: not too sure if we’ll see that much change here but I am curious to test a frame with a much steeper head angle than current bikes have and combined it with a short stem (kinda like your idea but keep the wheelbase the same). Longer wheelbases might help with a couple of moves but it would compromise others, current wheelbase measurements are a decent middle ground. I do think having a shorter stem could make things like hanging hooks easier though as there’s less leverage in the stem wanting to twist whilst your weight is on it. Current bikes with their long stems put the bars so far out in front the bikes effectively have a 90 degree head angle anyway.
tech: the biggest advancement I can see helping with comp trials is utilizing flex in frames to act like a spring and increasing height of moves. Frames are like pole vaulting with a stiff pole, imagine if you could preload the frame like you do with your tyre (and a pole in vaulting) and use that energy in a gap or sidehop…I’ve absolutely no doubt this will be the future but it’ll take a lot of cost and development to make it work