At my Met area club we have arrived at a place over the last ten years or so, where we foster a pretty good caddie program, have local scholarships and Evans Scholars, and a good mix of HS/College kids and well as 30-50 year old caddies, most of whom are doing it as a "weekend job" to go with their day job. We don't mandate the use of caddies, or even carts or forecaddies, but our club culture for weekend mornings is that its "strongly encouraged that the members support the caddie program". That said, about 11 percent of our weekend morning rounds people walk and carry. Another 30% or so take a cart. We are a very busy club (>22k rounds), so there are plenty of caddie rounds to support a lot of caddies.
During the week, there are many more walkers and cart users, but caddies are still available at all times. We use the foretees system to schedule caddie loops, so that they don't have to hang around hoping for a loop. They can go online and "take" a loop, or be assigned one.
Lastly, we have A, B and C caddies.....Members/guests can request whatever they want, "A" being a very experienced caddie, likely wants two bags, and will interact with you as much as you want, or not, and will be very knowledgeable and efficient and frankly is part of our Club family in their relationships with the members. "C" being a young bag toter who still is learning.
Al of this seems to work pretty well.....