I'm no financial whiz, but there has been plenty of examples of companies buying up other companies that are bleeding money. This almost always does not end well. It seems like the time to buy is after they've already bled out (i.e., in liquidation mode). This would also raise the spector of more US jobs lost.
Yeah, this deal doesn't make sense to me either. Just let them die, then feed off of their carcass. Viola! One less competitor for free. There is definitely not $4B+ worth of value there, and that's way too much to pay just to say you're losing less than everyone else in DRAM.
I'm not sure if this merger really can bring advantage to Micron at the end. It seems the only likely scenario is that the profit margin of Micron will drop further while it is still hard to say if the price can stand firm.