If we take into account how much payola Jungkook will be given if he releases an English song, I can see Jungkook being the only relevant soloist in BTS. We have all seen how even though BTS are allegedly the biggest group in the world, the failure of Suga, Jin, Jhope, and RM's solos. Poor streams, poor charting especially in Korea, poor sales.
If V puts out a solo song no one will understand what he's singing because he always sounds like he has something stuck in his throat and Jimin... people will file a complaint to the radio stations if they hear that screechy voice for more than 30 seconds.
Jungkook, although a poor vocalist compared to the likes of Rose, Beyonce, and Whitney Houston, has a voice bearable enough to listen to given the right amount of autotune