The answer is that it's lucrative but only in the long run, after a very expensive up-front build-out. And Wall Street doesn't like lots of short-term pain for extended long-term gains.
The hypothetical scenario we were talking about is: What if AT&T had taken all that cash they paid (i.e. debt they incurred) for buying DirecTV and instead spent all that money on FTTH deployment? The answer is that, in hindsight, it would have been the MUCH smarter long-term move. (Hindsight is 20/20, of course. AT&T didn't realize that linear-channel cable TV service was peaking right when they bought DirecTV.) But in reality, Wall Street would have punished AT&T for spending so much money at the time on FTTH because the payback would have taken so long. So had AT&T *not* bought DirecTV, they probably wouldn't have instead done FTTH.
Still, though, it's an interesting hypothetical.
As for what's the incentive to switch from cable to fiber? Well, for one, fiber has a reputation of being better, more technologically advanced. And it is. But even setting that aside, if a second broadband operator comes in and can offer a product of at least equal quality to cable, with the same or slightly better prices, and they advertise it enough, they'll end up with close to 50% of the market in time. It's just what happens. Folks tend to *hate* the local cable company. Even with FTTN Uverse around here, AT&T got a nice big chunk of the business in Nashville. That'll only go up now that they've converted most of the area to AT&T Fiber.
