If somebody tells you that [insert champion here] is wrestling [insert returning superstar here] next week, it's a Title match UNLESS they specifically call it a non-Title match. That's a pretty valid assumption.
What about the Piper-Hogan match from 1996 where Roddy won clean and didn't get the title because the match was never announced for the title.
It's only a huge showdown if BOTH guys get more over than they are right now. I love Brock and he's doing awesome, but he's just not popular enough to give it a Rock/Hogan feel right now. Who knows -- perhaps by Wrestlemania he will be?