That 8th reliever spot is just so negligible, especially if Ross is also stretched out for multi-inning. Last April they opened with Nick Nelson and Connor Brogdon in the bullpen, and then Ricardo Pinto for almost the entire month in place of Brogdon. (Kerkering reclaimed the other spot, the 8th was meant to be Ortiz).
It also didn't seem like Walker struggled with the bullpen role or routine per se when he finally had to do it. He just couldn't pitch, period (but was arguably better in the odd relief outing, which I believe is how he wound up back in the rotation one last time even).
But if there's any market for him at all they probably move him. As much trouble as they had last year filling the spot after Turnbull, this rotation is still pretty ridiculous 1-5, and last year's team still won 95 games. If they have to go with Ross or Johnson as a #6 here or there pre-Painter they would live.
In 2023 the first month's rotation was Strahm and Falter. Ranger was out, and Sanchez wasn't yet a consideration (he was also hurt). Falter was briefly replaced by none other than Dylan Covey before Sanchez finally came in.