You might start seeing a shift in quality but the warning will be funky leaves etc. This I guess can happen from sub optimal care or damage during the taking of cuttings, infections are what not.
If you take plenty of cuttings and pick the healthiest looking ones while giving them the best environment they should be ok, people have done it for years. I do tend to think that even in the best situation they will slightly begin to fade over time. I mean if you compared a 30 gen cutting to a second gen of the same original mother you might see a noticeable difference in vigor and certainly structure.
I've never seen any official testing to say one way or the other so it's pretty much speculation on any decline in potency/yield (although it would be very small amounts most likely). Unless others have more info on it?.