How hard is it to mergemine?
I dont think miners will have to choose.
How hard is it to choose not to go bankrupt? I dont think many businesses will drop one coin over the other, they will just pretend they are both normal bitcoins. we will just have some growing percentage of bitcoins that are split and thus dramatically increasing the coin supply. not overnight, but over a period of 6 months, we will probably get to where the majority of dualcoins are split, just via normal transactions tainting the dualcoins into two.
I think they can not mergemine since they are mining on different chain by that time
The coins are doubled, however the ecosystem can not double over night, if suddenly the money supply increased by 100% but there is no increased demand, we will get a zimbabwe coin