I don't see the MID's being an initial threat, but I do see them getting better. And the one thing that I see setting them up as an eventual winner over the NITs, if they NITs don't resolve this, is that several of the MIDs have a plan for HSPA WWAN support.

The NITs will need some form of included WWAN that actually has a sizable market footprint. And probably soon (sooner than WiMAX will get them there). And, no, tethering doesn't count for this requirement.