Killer of Chains
First real drivetrain upgrade in years
My current drive train of Hone cranks, 2005 XT Rear Derailure and 1995 XT thumb shifters have been in use for oh...6 years? The thumb shifters will be reliable for centuries, so they don't need replaced...but I haven't had triggers in ages.
The derailure is finally giving up the ghost, thumb shifters are nice but not compatible with everything, and the rings...who knows.
What's a good upgrade path if I still wanted to shift (aka no single speed) using my thumbies?
If you're working fine with an '05 der, you can probably get away with any 9 speed shimano deraillure. What do you mean "giving up the ghost"? Shimano derailleurs don't really wear out like "other" manufacturers.Unless you have damaged it, or have a lot of play in the pivots, it should be fine.
Might need some thorough cleaning... Worn pullies aren't an issue as long as the chain stays on them.
It's most likely you need a new cassette, chainrings and chain. Probably replace the shift cables and housing if you haven't in the last couple years.