The future is probably much like the present. There's enough of a market to keep them around but they'll never get cheap enough to come close to supplanting cheap ARs because there's just not enough volume. Since most military bullpups are full auto, there won't be any entering the US via the surplus market. You might get a parts kit but then how do you get a receiver? All this meaning there won't be cheap former military bullpups available.

The prevalence of 5.56 NATO also doesn't help their popularity. That round has kind of hit it's limits in terms of effectiveness. Manufacturers have wrung just about every performance improvement they can from it. If you want longer range, you need a longer, heavier bullet that bucks wind better. If you want better short barrel performance, you need a bigger bullet. But 5.56 is THE standard many armies have agreed upon, so the improvements offered by the newer gen of intermediates like 6.8 SPC, 6.5 Grendel and 6mm ARC are largely going to remain a niche thing. And now with the ICAR using a different magazine (shared with the LWRC Six8) than STANAG, fragmentation only hurts adoption. Plus the US army went full r-slur with the M7 and 6.8x51. So you don't get the full benefits a bullpup offers and NATO militaries get adequate performance from 62gr M855A1 (or their equivalent) already.

And Internet operators have declared that ergonomics are incompatible with their desire to not actually train with their rifles and thus a reload that takes mere milliseconds longer than AR15 means instant death in a fire fight.

Bullpups are better, but they're not better enough than an AR to merit a change.