I never doubt the quality of Kyle Walker, but I don't think Bayern Munich will sign him. If they transfer, it would be a good challenge for Walker, of course. I think he will go to Saudi Arabia to earn money because a 33-year-old football player will want to earn serious money in his last days.
At that age it's time to think about money over career and I think that's also a very natural thing for him, but if there is still an option for a better team in a more popular league I don't think Kyle Walker would be wrong to go there either. But in this case I agree more that Kyle Walker wants to consider more money than continuing his career which will eventually be released by the team that signed him at that age.
Anyway, Kyle Walker has already get many titles with Manchester City so indeed, it is quite reasonable that Kyle Walker might prefer to earn more money with playing in the Saudi Professional League. After all, even if for example Kyle Walker left and joined Bayern Munich as well, in fact Bayern Munich basically only has dominance in the Bundesliga but not the Champions League. Thus, choosing to play until his contract expires at least for one more season at Manchester City and then leave to playing in the Saudi Professional League, at least i think it will still be a reasonable choice and still feasible for Kyle Walker who is approaching retirement.