I doubt that they can keep travel credit and net that against the annual fee refund. That would seem to be a violation of the CARD act.
USB did what they could do minimize gaming, by making it membership year based, rather than CY based.
Ultimately what they would have to do is make it like some the hotel cert/FN which only 'vest' into your account 30-60 days after renewal.
I doubt that is so easy to do for a monetary credit, or that it wouldn't cause other problems like irate customers calling up wondering where their credit was, which would soak up CSR time.
Anyways, here's a dp from reddit, although not super recent
https://www.reddit.com/r/churning/co...dqj/_/dzuu6t6/
Given the use of this card I think it makes sense to leave open anyways as the net economic cost of keeping it open is either very low, or even negative if you get the 10k retention.. Gpay, Apple Pay, etc. are only getting more prevalent. And no dealing with the category/MCC coding BS that Amex Gold folks have to struggle with....
I do grant that one cant MS on it, and that otherwise racking up scads of their proprietary points is hard, since they dont have a whole ecosystem to support it.