I think this is completely different and is like how Matt sings Tom songs now. The replacement usually sings the original songs. I'm talking about when an original singer returns and does not sing the replacement's songs.
This makes me think of Further Seems Forever, which is a whole weird situation in and of itself... but during the Penny Black era did Carrabba ever sing HTSAF or Hide Nothing songs? During reunion shows didn't Jason sing some Hide Nothing songs? Part of me would like to hear Tom's take on Skiba's parts, but I'm also totally here for blink as a 4-piece! Even incorporating all three vocals could be cool!
A couple examples I can think of where original singers returned and sang their replacement's songs are Taking Back Sunday and Kansas. Chiodos is another example where the original singer returned, and they stopped playing material from when he was gone.
I would push for a 4 piece and then have them just do punk versions of beatles covers but rework some lyrics to "When I'm 69" or something.