I agree with Jeff Gutt as a potential new vocalist.
Michael Barnes of RED is also a good choice. His voice also sounds similar to Chester. He can scream and sing. He can do both soft and heavy songs. You can definitely hear Linkin Park influences on RED's first few albums.
https://www.youtube.com/watch?v=KQjOK3e5sCU
https://www.youtube.com/watch?v=4OUHoFAziyU