Block size could reach the 1mb limit at any time with a massive influx of users and the chart for average block size looks like it could possibly have a sharp exponential rise hitting the limit within a short period of time, well before March 2016.

IMO, even Gavin may be to late.  Most likely, if this increase in adoption happens, transactions will be pushed off-chain to Coinbase and other services until the limit can be increased.  Anybody opposed to the block size increase doesn't even have a working solution for scale, so I don't see how their arguments can even fly.