Sure, they could get a new bassist, but the point of the post you replied to (I'm pretty sure) is that without Andy it wouldn't be The Smiths. Andy's bass melodies were ingeniously interwoven with Marr's guitar melodies to the extent that I'd argue he deserved a co-writing credit. His role in The Smiths was hugely under-rated by both Marr and Morrissey. And yes, they talked about replacing him at one point, but that reminds me of Lennon talking about "getting Clapton in" when Harrison temporarily quite The Beatles.
It's not to say Morrissey and Marr couldn't do anything worthwhile together now, but it wouldn't be The Smiths. Although, with the passage of nearly 40 years, it arguably wouldn't have been The Smiths anyway, even if Andy had survived and all four had got together again. Another time, another place.