Yes you right, USB stick could be compromise in this case but with more problems, not sure if I like that compromise though!
Also i'm surprised that 4G/LTE connection appears to be so rare. Technology out there already more then 2 years, and we are in Dublin have perfect - nearly full city coverage. Also there are plenty complete solutions (f.e. mentioned USB sticks from various vendors), and there are shields with GSM fro arduino, im surprised that for ~2 years nobody had needs for updating old GPRS shield with new LTE modems.
4G/LTE connection is way more handy especially for wearable devices as WiFi or BT limited to range of single spot which is incomparable to mobile network coverage.
Anyway, if you guys find about new shield/modem available for reasonable price (not 300$ for 1 module) - then please update me