I asked the same question here on LA LA Land's Craigslist.
RKC replied:
That's Jerimy Chambers building new rails for Brunswick tables, he'll find out the market place won't support what he's thinking is going to be a gold mine. The end results are you receive a new set of rails that are not fully finished, they still require the rail trim from the old rails to be transfered to the new rails. If you have GC1, you better hope and pray the trim fits on the new rails or you'll never get the rail blinds hooked up. If you have a GC3, you have to remove the trim and remount it on the new rails....and, you're relying on the local table mechanic to to this work if you're a customer, which still does nothing to straighten out the rest of the table to make it complete and playable. Mark Gregory and i talked about this and we both agreed, we'd never buy new rails because we rebuild them new anyway.
I'm not so sure that I buy this argument...
Swapping the trim is easy. The only time that it's a problem, is if the screw heads are destroyed. Even that isn't a huge issue. Since these rails are produced as a direct replacement, I can't really see much reason why the old trim wouldn't fit. What would be really nice is if the new rails are pre-drilled for the trim mounting holes.
As far as relying on a local technician to do the install: I would think that if a customer is dumping the kind of money that it takes to purchase new rails or have his rails rebuilt, he will likely make sure that he has a reputable technician to do the install..
The major benefit to purchasing new rails, over having rails rebuilt, is that the new rails will actually look new (with a choice of finish), as opposed to the old worn out or broken formica.
I think that it all comes down to price. That will determine whether or not there is a market. Even still, I don't think that it will have too much of an affect on the other technicians in the line of rail rebuilding.