Saw Journey in March of this year with Arnel on lead vocals. They filled up an 18,000 seat arena. Great show. They were also inducted into the Rock & Roll Hall of Fame this year. They are still a very active touring band.
Journey got lucky when they found Arnel. It’s hard to change lead singers and still keep the same sound. Other than ACDC I can’t think of many bands that have. I can think of lots that tried and failed.
Guitar players are a different story. Neil is very good, but there’s probably 100 guitar players in LA and the Bay Area who could step in and play all of their songs and sound great.