I'm not really happy with Cap's casting either, but I'm trustin Evans to do a good job. He's a competent enough actor, but I'm not sure he can fit the bill without sounding cocky or preachy. I think it all comes down to how the character is written.

Either way, I don't think it will ruin the fandom. There will probably be a huge influx of new fans with the new movies, but with the bad comes the good, fandom growth isnt always a bad thing.