There seems to be a common assumption among mobile broadband operators that when they put bandwidth caps on their offerings, most users will still only exploit a fraction of their allowance.
This is probably just as well, as there are strong signs that the underlying per-GB cost of many HSPA networks stacks up rather poorly against the revenues per-GB if customers do actually use all their allocation. In the UK, 3 is giving away 15GB per month for £15, for example.
At that price, I'm wondering if there's a risk that operators start attracting the "wrong" sort of customers.... for example other operators. OK, it might not be ideal to run GSM voice tunneled over HSPA, but imagine if that 3 dongle (with its 15GB per month) was hooked up to one of Vodafone UK's new femtocells.... not a bad way for Vodafone to improve its backhaul economics, perhaps? Especially where its customer doesn't have an ADSL line.
OK, I'm sure there's some stuff in the terms of service which would prohibit this. But it wouldn't surprise me if some operators unexpectedly become wholesalers of capacity, if they price their retail services too low, in the hope of winning the marketing "who's got the biggest cap" war...