Here's the issue as I see it (as do many other missiologists):
A church with a largely older congregation has probably locked into a PARTICULAR cultural expression. This seems to be more true within a church than outside its doors, and that largely due to the homogenius make-up of those church members. While they are indeed part of the "set" that is the world, and part of the "set" that is their community (with all the local flavor and culture), they are also part of another "set" that largely defines their worldview and that "set" is the local congregation that they have invested their lives into attending, leading, giving, serving, etc.
Because they are removed from the cultural norms (for the most part) because of their smaller contained "set" (church membership) they tend to have no real motivation to change their culture. In fact, if anything, the church offers to them "insulation" that assists them in rejecting the larger culture of the world around them. So, while they likely do participate with their community in general, listen to some similar radio and watch similar televion stations, and generally dress in a way that allows them to blend with their community, their particular "set" finds them more locked down than the general community, with trends in music, dress, workdview, culture, etc., lending creedence to ONE PARTICULAR STYLE --and that largely "the church they remember" and the "church they inherited from their parents."
These two issues mean that the congregation is anachronistic to the populace at large in the community and they likely take pride in the fact that someone who wishes to enter this particular congregation would need to "swim upstream" in order to successfully blend with the balance of the movers and shakers. This is likely even expressed verbally with some sense of pride and satisfaction, i.e., "We do church right and everyone else is changing the gospel, singing songs that are not of God, etc."
Therein lies the rub... The greater community around the church doesn't care that the people within the church prefer a 1960s model, a particular (and perhaps even "weird" or "peculiar") church culture that does not match its community, or that they must adopt the churches culture in order to fit within its "set." They just go elsewhere or not at all, largely depending on the overall culture of the particular community.
So, the church that is proud of the fact that they do church right, make other swim upstream to become members (and note I'm not talking about gospel imperatives here, this is a cultural issue), and where, generally, one must become "weird" or "peculiar" like the congregation, will die as members die off one-by-one.
The best way, in my estimation, to handle this issue is to instill a new culture in the church -- don't ask the people to change, they'd rather die! -- but instead, a culture that wishes above all to leave a legacy. They can BEST do that by planting a new congregation right within the walls of their existing building. Get on board with a new church start in the same building, call some younger solid folks who are theologically sound, and give them a few resources and let them fly. They will look different, act different, sound different, and do things differently, but at least they will be doing all that instead of not.