This has come up before and basically what was concluded is that if Catherine gives Henry a son he won't seek an annulment since it would mess with the succession of the son he does have. Instead he'll fool around with mistresses, recognize any male children that they have (since they could be possible backups), and just wait for Catherine to die of old age since she is older than him.
If she dies before him, he'll get remarried in a heartbeat.
If she dies before him, he'll get remarried in a heartbeat.