Integrated data plans on a tablet form factor is a niche product, bcs it will never be your primary personal comm device, nor will it be your primary data computing device. It's most likely going to be your 3rd data service--following your smartphone, and whatever you've got your laptop/pc/home network running on.
For international travel, the best pairing of hardware is to sever your hotspot from your handset/tablet; get a mifi type device, and run your 3G or 4G from there. Personally, I prefer this, even over the option of tethering to a smartphone. There are several reasons why this is advantageous. You get the benefits of tethering, which means you can run your service to serve your smartphone, your laptop, and your tablet, and whomever else you want to share your hotspot with. Meanwhile you can run your phone all day w/o killing its battery. Speaking of battery life, you also don't have to be sitting within a power-cable's length from an outlet to use your phone when it's tethered. Plug your mifi device in across the room, and act like a normal human being, not some borg. The fact that you can tether to your phone, is imo, a nice backup plan. But it's lousy for a primary mode of operating, because it *really* kills battery life.