just because Muggsy could be 100% effective at SG doesn't mean there aren't four thousand other guys that will be better at SG...
To my knowledge, they're not changing the engine. So there's absolutely no reason you'd ever want to put Muggsy at SG and try to win a championship, so that minor irritant is infinitely outweighed by how nice it would be to have other players available for 2 positions... I mean, I'd love to use Wilt and Shaq together, though that might not be super realistic. I'm okay with that. This is what if, after all. Right now we're living in a reality of bombers dominating, so I'm okay with a couple of guys playing positions they probably never could.
Positions are really outdated, anyway. Tim Duncan started at PF for most of his career, but he played the role of a traditional center. I think there are really four positions... big man (pf/c), forward (sf/pf), wing (sg/sf) and guard (sg/pg). Most players fall into one of those four categories... guys that can fulfill a role traditional to one of the positions on offense and cover both on defense. There are very few guys that I would say are strictly one position or could only play that one position.