I would expect the Surface Pro to have this, but RT will never have LTE or any cellular connection, as it doesn't have GPS built in. Not only would Microsoft have to implement GPS, but also the CDMA/WCDMA into the already-cramped tablet. Like I said, Pro could bring something new to the table, but as for WinRT...I wouldn't keep the porch light on.
Look at this Windows 8 RT Tablet with LTE and HSPA+ for att. I think Verizon will have an RT from Samsung or the Surface either December for spring 2013. I don't think they will fall that far behind.
I for one wouldn't mind paying $10 a month for a Windows tablet. Get to upgrade every 2 years to the newest model, and not have to shell out $1,200.00 at once for 2 of them. (For the wife and I) With AT&T offering one I hope Verizon at least TRIES to stay competitive.