Seems like a non-idea to me at first glance.
You can already fork all the new source codes (incl. Bitcoin), like NXT and get a share in the fork for nearly free except the way they do it now is better!!
They announce it on the Bitcointalk forum and make a new community who might be interested, active in challenging the original (Eg. NEM) This is far better than randomly airdropping the free clone to all Bitcoin users.
(Even a new source will have attracted investment and a community during it's construction phase so will have an actual marketing & development budget and viral marketers that a fresh clone can't compete with. It can also create add on services & features a clone doesn't have access too.)
The only situation I was worried about was if a vulture had a great marketing team and industry contacts related to the project they can create clones that can challenge the original. (Which is why I highlight marketing in 'things I'm most worried about' ) But just airdropping to existing Bitcoin holders Pfft. (I guess if it did become an issue, the developers the new community trusts, could in the beginning make some stuff closed source till adoption reaches X market size?)