lol 750M difficulty is like... what? a few months away?
Current Difficulty is 50M, assume 20% increase each change... that's 15 changes away. 5-15 days between.
50,000,000.00 0
60,000,000.00 1
72,000,000.00 2
.
.
.
1,597,399,996.85 19
1,916,879,996.22 20
See, available hardware will limit that. Math can't get the the way of common sense. Currently, the network it at ~500 terahashes/s, with a difficulty of ~50 million. For rough estimates, we can say that the network is 10x the difficulty. So, if we have to hit 750 million difficulty, that is a 15x increase in difficulty, which would require a 15x increase in hashing power, raising the network to 7.5 PETAhashes/s. There's no way any ASIC companies can deliver that much hardware that quickly.
The estimates that make sense to me are about a 3 petahash network by the end of the year, which would give a difficulty rise of 6x, which sits us at 300 million, well below our 750 million cutoff.
Difficulty cannot keep rising at this speed, it has to level off at some point. And my guess (however little it may be based on) is that that level-off will be around 500 million difficulty.