Well, I personally think if an adventurer cameo is about to happen, it should be Elminster first.
Elminster had a connection to the original plot and was not just a cameo. If there is a connection between the games, he may remember his interest in Gorions Ward and actually look into it.
Drizzt was just a random cameo in 1 and a helpful cameo in 2. He never had any connection and was just added for the VIP factor.
I would not mind seeing neither of those, though. They are, at least for me, walking reminders of the problem with old adventurers.
They have done nearly everything and every time they appear they stumble upon their own enemies, because otherwise there is no reason for them to not solve the plot.
I know they are popular, but sometimes I think they should retire. I.e. let a kind-hearted drow stumble over a study about him in the underdark and s/he wants to become like the great Drizzt.
Bottom line, if they appear, they should have a good reason for it and, if possible, let it be a forgetable encounter for them.
Not neccessarily for the group or other npcs, but for this kind of adventurers it should just be a tuesday..
