(...) You won't get side-chains if you stay on the 1MB block chain, because the 1MB block chain will not move fast enough to support them. (...)
Can you elaborate? First person I hear making this claim.
Even after a new version of the software containing a hard fork is deployed, the new protocol does not actually go into effect (the hard fork does not actually happen) until more than 95% of the hashing power is ready to go onto the new protocol.
That leaves less than 5% of the hashing power on the old protocol, meaning a new block on the old protocol could be found less than once every 3 hours. Because that's clearly a loss and a failure, at least 90% of the remaining people would abandon it immediately, leaving it getting one block about every 33 hours. Making it even more a loss and a failure, but assuming that last half-percent of the hashing power can be an irrational lunatic fringe who never ever leave, then with that amount of constant hashing power....
The transaction rate on the old chain is one transaction per 86 seconds.
Most transactions never get into a block on the old chain, because the blocks are only 1MByte and only happen once per 33 hours.
If a transaction does happen to get into a block on the old chain, it will be ten days before it gets to confirmation depth.
A coinbase from finding a block on the old chain would take four and a half months to become spendable.
And 2016 blocks, which is the time between difficulty adjustments, flies by in just seven years and eight months. The maximum adjustment an unforked bitcoin will allow is for the block speed to quadruple. Therefore the time to each new difficulty adjustment is a quarter the time needed for the previous one. Again assuming hashing power stays constant, which it won't:
You spend seven and two-thirds years getting blocks once per 33 hours. (1 tx per ~86 seconds)
You spend a year and nine-tenths getting blocks once every 8 1/3 hours. (1 tx per ~21 seconds)
You spend five months and 20 days getting blocks once every 2 1/12 hours. (1 tx per ~5 seconds)
You spend a month and twelve days getting blocks once every half-hour. (1 tx per second)
And after that difficulty adjustment works "normally". It takes ten years to get back to handling 1 tx per second.