Core is working on a 2mb hardfork proposal, testing is in progress! Amazing news

4) Some of us also agreed to work on another hardfork proposal including a 2 MB "no wallet changes necessary" block size bump, which we've been making progress on over the past year, including even after conclusion of the original agreement (there is currently a testnet for an incomplete version running).

http://np.reddit.com/r/Bitcoin/comments/5gcg98/will_there_be_no_capacity_improvements_for_the/darfdyg/

It can be phased in, like:

if (blocknumber > 115000)
    maxblocksize = largerlimit

It can start being in versions way ahead, so by the time it reaches that block number and goes into effect, the older versions that don't have it are already obsolete.

When we're near the cutoff block number, I can put an alert to old versions to make sure they know they have to upgrade.