I don't really care anymore to be honest

(see last paragraph)
...since WOTC seems to be trying hard to unite fans of various D&D incarnations, we could see the 4E Realms timeline go the way of the do-do. .
Rather like what happened to Dragon Lance... except this would be at odds with the egos and vanity at WotC. So, for that reason alone it probably will not happen.
WotC does not release sales figures, but there is wide speculation that 4E commercially failed. If 4E failed as a whole, how could 4E F.R. - by definition a part of 4E - succeed.
My own hatred for 4E F.R. went beyond the RSE, to include the lowered words count, lowered reading grade level of the book, poor over all organization, often mediocre art, non-existent index and piss poor table of contents. The RSE were just insult added to injury. Assuming there is a 5E F.R., WotC should make it an improvement on 4E in terms of word count, reading grade level, art, organization and over all composition compared to what 4E F.R. was.
But that probably will not happen.
In terms of canned settings, these days I like Eberron. It is a fun place to be. I no longer care about F.R. over much and have purchased neither game books nor novels for a long time. As Jake put it, "Go on then, there are other worlds than this."