"Today on the Sourceforge hosted Bitcoin-development mailing list Gavin Andresen has threatened to leave his present group of Bitcoin software developers over their objections to his demands for a rapid hardfork of the Bitcoin network. In the event his demands are not met Gavin plans to join Mike Hearn's Bitcoin-XT project which is a fork of the Bitcoin client where Hearn implements patches that Gavin's current affiliated developers find too risky to implement in any mainline Bitcoin client. If Gavin defects to Bitcoin-XT he plans to work with Hearn to lobby merchants, miners, and businesses to move to Bitcoin-XT. Previously Mike Hearn was responsible for the March 2013 Bitcoin network crisis."
Original post: http://qntra.net/2015/05/gavin-threatens-to-quit-bitcoin-development-and-join-hearns-fork/Such a move will only weaken Bitcoin's credibility in the eyes of the public.

You can bet that if this happens some altcoins will be able to suitable spin it for their benefit. Even a 1% movement of money away from Bitcoin to a particular altcoin will make their marketcap shoot up.
So be prepared to get a lot of negative marketing from within the community itself, not just general public.