A second PoW period is still under discussion, but it does appear to be the best available solution to growing the MastCoin community, barring a substantial change in the current situation. Keep in mind that if adding a second PoW period increases the size and involvement of the community, it likely will increase the value of each coin, regardless of any increase in the total number of coins.

One solution to reducing any potential impact from increasing the number of coins would be to keep the total number roughly the same by lowering the PoS interest percentage to compensate.

My initial guess would be that if there was a second PoW period, it would not have SuperBlocks, and it would take place over a longer timeframe than the first one.