I've been with contact with Robert Pontow from Deep Silver, who is working on Shenmue 3.
I told him about Eric Kelso, Paul Lucas, and Lisle Wilkerson, and how they want to return to Shenmue 3. This is his reply:
Hi, thanks for contacting me. Would you have any email addresses of the voice actors, their agents or any other means of contacting them? Unfortunately I wouldn't be able to discuss anything over FB, so we would need to take an official way to get in contact with the voice actors. But I am sure that Yu Suzuki would be happy if we can secure the same crew for Shenmue 3. Best regards
This means there is hope yet. I will try to find a way to get in touch with those three, I'll tweet Shenmue AM2 podcast who had been in touch with them recently. If you guys know anything that might help, let me know too
This also confirms my suspicion that they didn't know that the VA's wanted to return