This use of the term "altcoins" is a name people throw around to be derogatory. Any Bitcoin hard fork could be considered "an altcoin", so unless you plan to get a blocksize increase with a soft fork, prepare to be using an "altcoin". Bitcoin will become what it becomes, regardless of what name you give it.
Which is more hyperbolic, using the altcoin slur or saying that the block size will never increase unless we adopt the XT client?
We need more transaction capacity, is increasing the block size the only way to achieve it? The answer is no. And none of the devs, again, not even Gavin, think that. It's the most crude way to do it, and it comes with the most problems also.
Getting rid of the block size limit
will be a part of the successful idea that increases transaction capacity. But it will not be the only part, and it will not be the most important part.