I'm starting a new thread since the existing one is for new line or port in.
I called Xfinity mobile customer care to ask if they are offering any promotion to existing customers to upgrade to latest iPhone 11 phones and I was informed, in no uncertain terms , that I'm eligible for $250 Visa card if I were to buy a new iPhone 11 (Max or otherwise). He even read some written promotion to confirm when I told him I was suspicious of that offer. I even pointed out their website states that a new line or a port in is required... but I was informed that is not required.
The only requirement is I will have to buy the phone at a local Xfinity store.
Recommended: Place your order for the new iPhones on or after September 20th, 2019 *IN STORE ONLY*
Try your luck at your local store. YMMV.