ever since the ipad 1 came out, the only company in the united states that offered unlimited for the ipad was AT&T. I'm skeptical verizon would allow an unlimited sim card in an ipad. it might not work. all is not lost.the ipad is unlocked. shop around, you could get a prepaid sim , or a free t-mobile sim
i never heard of any cellular company except AT&T offering unlimited for iPads.
the next best thing to unlimited would be a post paid T-mobile account 6 gb or more for $35. this would give you binge on unlimited music and video streaming and a data stash of 20 gigs and tethering.
please don't decide not to buy it based on anything i say, try it and find out
however, if verizon won't enable the hotspot feature, there is nothing you can do to enable it, without jallbreaking. and running a hotspot app from other app stores.
if verizon catches you using that app. it might mean doom, they might cancel your service.
i heard t-mobile started to crack down on those hotspot apps and they were able to find people that use them and they lower their plan
a cellular iPad does not need to be attached to your iPhone plan. this gives you the perfect opportunity to try other carriers like AT&T, sprint, veriozn, t-mobile, etc etc
you could keep each one for a month , cancel. and come back
the apple sim ( in the air 2 ) would give you 200 mb for free on t-mobile to play around with