I have no advice for you other than to find a politcally-correct way of telling those slackers to get with the program or find a new job! Just because they may retire in 1-5 years does not give them an excuse to sit around doing nothing while the company tries to progress in Revit. I'm a member of the older generation you describe (42) who started out on the board, made the switch to CAD, and am now embracing yet another paradigm shift to BIM, but (unlike your co-workers) am thrilled to witness the evolution take place while I am still in the business. As a CAD Manager, I know how hard it is to motivate people who are complacent in their current position/role, so you are going to fight a neverending uphill battle, but to hear that you have unproductive senior drafters sitting around making big bucks for doing nothing while the junior guy does all the work is just appalling. IMHO management needs to shake things up and make some threats, but I digress...I'm preaching to the choir and without management's backing, you have a no-win situation on your hands
Good luck, you'll need it!