If we can recast a genesis block every 20th block as part of the routine operation of the NXT blockchain, we have accomplished something very, very special - a self limiting blockchain that grows very slowly.
A blockchain needs to be as long as longest possible fork, at least. I don't know, half a day? Definitely not 20 blocks.
1440 blocks is the limit for blockchain reorganization if I'm remembering correctly. So it would have to be just beyond there.
Let's call it 1500 blocks between pruning / re-genesis to be on the safe side. 1500 minutes = 25 hours. So for a testnet to generate three genesis blocks during its run to prove that's a routine thing, it needs to go 75 hours, or three days and three hours.
Total number of fake transactions that need to be broadcast during a NXT 3+ day pruning 1000 TPS testnet demo run are 3*1500*60*1000 = 270 million. At 128 bytes per transaction, that's just under 35 GB. SO the block chain grows by say 12GB between pruning and re-genesis. The Bitcoin blockchain is currently at just under 14 GB: https://blockchain.info/charts/blocks-size .
So with the proposed 1000 TPS testbed with re-genesis every 1500 blocks we are saying that when NXT gets to the current Bitcoin blockchain size, we do something about it. They don't. Victory NXT. This alone make the project worth doing.
So does the requirement to let a 1000 TPS blockchain go over 1440 blocks / 10 GB in size to avoid forks mean that Raspberry Pis and smartphones are now excluded from the 1000 TPS testbed? Or is there a trick we can use to keep them along for the ride? Please discuss.
And somebody please tell me how you booby trap a genesis block so we've got to wait for source code release to start on this?