Could be. But United saw an increase of four percent year over year:

United Reports July 2017 Operational Performance - Aug 8, 2017

If US airlines simply increase passenger miles by 4% per year from now until 2035, assuming the average aircraft size gets no bigger, that would translate into a doubling of the need for pilots in the legacy majors from the number currently employed, and the United CEO is saying they are going to increase their year over year growth by 6% although that admittedly needs to be seen. Since the A380 and passenger 747-8 experience of huge passenger haulers doesn't seem to be doing real well, I'm guessing that increases in passengers per aircraft are going to be modest. In fact, if the E-jet E2s become the low end aircraft at the majors flown by major crews, the average might even come down, at least domestically.

On the LCC side, Jet Blue is expecting 6.5-8% year over year growth, while Spirit is currently looking at 14.8% year over year growth in passenger miles. While it is doubtful these numbers are sustainable over the long haul, even if they were only 2% that would still create a demand for pilots several times greater than all the pilots currently in the regional fleets even if all military fixed wing pilots trained in that period left the service as soon as their training-related active duty service commitment was up.

So yeah, Boeing may be exaggerating, they sell aircraft for a living after all, and no one can predict economic downturns or disasters, but it would be difficult to deny that the environment for pilot progression from the regionals to the majors isn't as bright as its been in our lifetimes. You don't have to be a Pollyanna to have a hopeful outlook.