Tales wasn't a remake - it was a sequel (just like the other three sequels made in the 90s) The voice cast in Tales (Guybrush, Murray, LeChuck, Elaine) was the same voices as in the special edition of Secret because they are the same actors who provided the voices in Curse and Escape as well

[1]
A special edition of Sam & Max Hit the Road may be nice, but I reckon the original voice soundtrack is fine as is, there'd be no need to replace it. Maybe re-record the music and fancy up the graphics, but that'd be it.
Of course, LucasArts (and presumably Steve Purcell) may have to reach an agreement to do this, and make sure it's financially profitable for them.
[1] I believe the voice actor for Elaine wasn't the same for Curse & Escape but I can't quite remember those details.