We do know Wally will be included as King has tweeted as much. Everything else is speculation and derivation based on Tom King's authorial history.
The majority of his life, the people who were by his side for his run as The Flash, don't even exist. If you think Wally is the sum of everything he was before 1987 then sure, he's rebuilding his life. But that's not the Wally I'm invested in.
For months on end Titans was about how shitty everything ended up for Wally. This isn't some massive revelation. The only thing since has been Flash War and Perfect Storm, neither the best outlooks for Wally. The only person he's connected with is Iris which was immediately cascaded into Wally hallucinating constantly about his ruined/lost life. These aren't cherry picking anything. If the entirety of the Titans run and what little he's been involved in Flash has been Wally being mistreated, miserable, or worse then what else is there? That one Nightwing cameo he had? What great strides has Wally made? That he has an apartment that someone else is paying for him? Wow, what a big step forward for a grown man.
If you're fine and okay with Wally just being a wannabe teen titan for the rest of his life then he kind of built some of his life back up, but even that he's been kicked out of. The fact of the matter is he'll never really get his life built back up because that would require him passing up Barry again. Or you defining and being happy with his life being nothing but a background character to someone else's story. Which I would be fine with if he was supporting the right character. Barry is not that.
But sure, let's just wait for the story to end. It'll definitely break the trend this time. Definitely.
The first nail in the coffin was Didio killing him off/getting rid of him in Infinite Crisis.
I don't know what run you're reading about when you say The Flash took a backseat to The Rogues. That was certainly not the case in the comics with the kids.
Wally is never getting back in the spotlight. Well, at least not for many years.