I'm a HW engineer. So my grasp on the SW is a little infirm. (Unfirm?) I'll leave the SW comments to the SW weenies.
It will take mining HW slightly longer to perform an SHA256 hash on 2MBytes of data, as opposed to 1MByte. It is unlikely to require a full 2x of time...but it's likely to be greater than 1.25x. (This is all "back of the napkin" estimation.) If I'm paid the same for a 2MByte block as for a 1MByte block, then I'll go for the 1MByte block because I can produce more of them in a given amount of time. This is particularly true if my HW is older (and thus slower) since I cannot compete as well at 2MBytes.
If there is free choice, at my level, then to persuade me to crunch 2MByte blocks, there would need to be a pay increase per block. The pay increase would need to meet or exceed the cost (to me) of the extra crunch time and extra electricity. Otherwise...if I am still allowed to crunch 1MByte blocks...and there is no "shift differential"...then I would never crunch 2MByte blocks.
i agree.. miners wont jump to 2mb instantly.. the 2mb rule is not an "average" but a "maximum"
it would in reality look more like like a slow increase.. eg 1.025mb, 1.05mb, 1.1mb growing slowly.. all of which are acceptable as the 2mb is a "maximum" not an average, and not rejected because the 1mb maximum is no longer inforce.
one part is as i said only when there is a majority of users able to cope with it (consensus) and the other is where transactions are pouring in and causing bottlenecks (filling mempools and risking mempool crashes if not handled/flushed sooner)..
where miners know if they let in more tx per block... even just 100 extra tx's(1.025mb) at first they can get an extra 100 transactions which means 100x tx fee..
again wont be a jump to full bloat 2mb in days.... i just meant 2mb POTENTIAL, which will naturally grow with time and user demand to send transactions
worded differently:
so imagine 1mb is about 4000 tx's maximum potential
it wont jump to suddenly hash 8000 tx's tomorrow.. it just means moving the goal posts, miners can hash out 4001tx's, 4010, 4100, 5000. blah, etc.. basically any number between 0 and 7999.. without the community arguing..
and the more tx the miner allows the more tx fee's it can eat