My theory? It will be both the Dark Phoenix Saga, and the Sentinels. They just won't make them purple ;) Good catch on who Hank was arguing with -- I didn't notice it.

And you're correct -- Shaw was involved with the Sentinels at one point: http://www.marveldirectory.com/misc/sentinels.htm

They don't actually show him, and you only hear Hank say "Mr. Shaw" over some of "Grace's" dialogue, so it was easy to miss.