One note though: Whether DRK will be profitable to mine or not, will not only depend on the block reward but also coin price. If, by the time X11 asics come, there are like 50-80-100 x11 coins, it might be the case that many of them might be more profitable to mine. The large number of x11 coins, is, in a sense, a guarantee for ASICs appearing at some point.
Sure, an abundance of X11 coins would make ASICs appear for X11. But, if none of them are pointed at a DRK pool, we still have The Bomb scenario, but then ANYONE could drop it.
How viable is it to somehow make it so that all the X11 networks are actually one network? You mine DRK, you shore up the networks of other coins as well.
Hopefully that makes sense.