I think he's definitely gonna be in the 26. Walker doesn't even play as a RB for England does he? He's one of the CBs I think. Hell, Trent was even selected Euros even if Trippier, James AND Walker was there admist rumors he wasn't gonna be included. Only an injury stopped him from taking part in that tournament.
Now if he's gonna play any at all. That is debatable, maybe a dead rubber group game if England has already qualified like the last World Cup.
And to cover his ass because if Trent gets left out, there's gonna be quite controversial and a big story and I think Southgate wants to avoid that.