If I drop Xfinity Internet and keep mobile, what do I lose and cost?

Hello,

AT&T Fiber is in my area now and MUCH cheaper than Xfinity (Yes, I called Xfinity and they can't do better pricing for current customers).

If I drop Xfinity Internet and keep mobile, what do I lose and what is the cost? 
I am at $45 a month, will it go up only $10 so a total of $55 a month plus taxes?

Thanks