Yeah. I'd agree on the RB issue, but not on Smith. Taylor will be relied on even more, so his value will be up slightly, but he's not having a stellar year, so only slightly.
Smith's value will go down considerably if Lefty is out for an extended period. You are right, a new starting QB will need a primary target, but that isn't going to be balance the need for a good QB/WR "feel" and practice time and decision making and all the other things that go into a WR's quality of production.
A RB, on the other hand, does not have to get used to a new guy sticking the ball in his sternum 3 yards behind the line of scrimmage.
If Jax had an experienced backup like a Brunnell, Gus Frerotte or a Trent Dilfer or even a Todd Collins, you could maybe feel a little better about JSmith, but David Garrad will be wearing diapers for a few games, so don't expect much out of the Jax passing game if the stories are true about Lefty.