Isn't it pretty much the opposite of what we saw happen with someone making a render of Techies looking exactly like Valve artwork for him( the one people think cyborgmatt used for his 1 april techies picture/video ) ?The community would make everyone near 1:1 ports of their wc3 versions, ignoring all the neat design choices valve has made and instead declaring blizzard is the best because of reasons, even if the audio/visual cues of wc Dota are awful and the choices valve has taken with certain aspects of character and skill design are far superior.
I think the community making hero could be used after the parity is done ( so by TI6 ), it wouldn't mean a new hero by month or anything, nor would it mean that they wouldn't rework it before putting it ingame ( from skill choice and balance, to animation, etc.. ), but I think it could bring some good design ( both visualy and from a gameplay perspective ) into the game; while also improving their release speed ( who am I kidding ? ).