They're going to kill Iris. It may not stick but I think she will be gone for some episodes. There is plenty of precedent in the comics. Reverse Flash kills her in the comics and for years we think she's dead until the last issue of Barry's series where it turns out her biological parents (Eric and Fran Russell) from the future had saved her from death, Barry lives with her in the future for a while, has kids with her (Don and Dawn) and then comes back only to die in the Crisis of Infinite Earths.
While most of that won't happen on the show I can see season 4 having a lot of characters show up from the future like Bart (or his cousin Jenni) and I think this is where the seeds for that will grow. There's going to be a point where Iris seems dead and Barry finds her living in the 30th century IMO.
Still wonder what they future Crisis event will be?
And why is Barry not going after RF now, since he is changing timeline?
And savitar claimed to be future flash, but how could that be, since he was said to have been first human in Speedforce?