Wouldn't changing the algorithm force a new blockchain for litecoin? That'd screw up every pool, exchange, client, etc. which is probably going to annoy a lot of the network.
And if that did cause some sort-of "litecoin 2", that would send the value of litecoin downhill, meaning anyone who currently has a lot of their money in litecoins, ends up with nothing...
Coblee has multiple options.
1) Drop support for litecoin1 and start litecoin2 or whatever, and give people all the existing coins in Litecoin1 into Litecoin2 (I did this with SolidCoin v2). Of course this also means the guys GPU mining still have their new coins in the new network but it potentially means you can start fresh with a new algorithm. It's a lot of work however.
2) Do a forking change in litecoin itself. The problem with this is the "old network" will continue in parallel with the "new litecoin". Which leads to a lot of support issues "Which litecoin are you on?".
3) Start an entirely new coin. Like he did with Litecoin over fairbrix. Probably the second easiest option to pull off since you don't have to support multiple old things and allows him to do some things from scratch a bit better. However the downside is the original Litecoins probably decrease in value due to no more developer (like tenebrix and fairbrix).
4) Do nothing. The easiest option.
The hardest thing is, unless you are well versed in understanding CPU and GPU architecture making a CPU hard coin is very difficult. Given Coblees failure to know if Scrypt was GPU hard are we going to believe he can now make one that is? This will require a lot of work and a lot of testing to verify. And you're going to need talented C++ and OpenCL coders to help you out I think.