So what happens in case of someone who is staking more than one coin in their wallet on old v.4 blockchain all day and hasn't been home to update to v.5 yet?
For other's that have had that happen, when you get v5 and re-sync, all your coins return to your wallet with the correct coin age as if they never staked in the first place. As long as coins were not moved, then once you re-sync to the correct block chain, it is as if the wrong chain never existed.