Hi lulubell, IMHO this is still unanswered. Perhaps one of the more experienced FTers can chime in, but I find seat guru to not always be reliable. Particularly in this case with the plane changes, the roll out of new product, etc. The only way to know for sure it to check the seat map online or by calling United.

Anyway, good luck. I hope that regardless of what happens, you have an enjoyable flight.