I think Scrypt algo should be hardcoded as for every 2nd block and for 3rd block some Proof-of-stake algo like PeerCoin does.
And generally include more PoW algos into Timetravel before we get a 51% attack.

so per blocks: random PoW -> Scrypt -> PoS with same block reward but randomly selected miner by coin age and total coin/spent coin ratio.