On the record high of unconfirmed transactions, would a 2mb blocksize house all that?
Arguably yes, but the effects that increasing capacity promote are more complex.
It's the psychology of supply and demand at work, in essence. The effects of more people using the network (as a result of 2MB or whatever blocksize increase) will, of course, increase the supply of the economic good known as the Bitcoin transaction.
But there is a positive feedback loop produced by that change, the increase in supply increases use of the network commensurately, people will simply justify using Bitcoin in further ways than they did before; new users are attracted by their increased opportunity to observe Bitcoin being used, existing users send more transactions because it's cheap to send again, and spammers will spam more, for their spammy reasons.
Metaphorically, it's similar to the problems of creating road infrastructure; when a new road is built, people just compare this nice new clean, empty looking road with the congested roads they already use, and some of those people come up with reasons to use the new road, and before you know it, the new road is just as traffic jammed as the old ones it sought to provide relief for.
The real answer is not more roads, as it simply begets more people buying and using more cars. A different transport paradigm is the solution, something that inherently has more capacity than we could possible imagine ways to use, we're looking for the Bitcoin equivalent of air travel or spaceflight, really.
That is the answer that I am afraid of. Yes with the word arguably. So it mean that some people can also answer a No and there can be an argument that an 8mb blocksize can also be still be made full.
