Nothing in mountain biking is truly new. Bikes have been around for a long time, and like Avril said, it’s all been done before.
Suspension? Yup, guys did that back in the late 1800s.
Curved seat tubes? Yeah, again, late 1800s. Those guys tried everything – clearly they were all over slack headtubes.
Dropper posts? Sure, we used to have that, it was called Hite-Rite.
Changes in mountain bikes are often about fashion just as much as they are about technology. I recall reading about a racer asking Paul Turner if he had a set of the shiny new, gold Rock Shox Mag21s they could use, and when he said no, but he did have some old, black RS-1s, they declined. Old in this context is from last season, which is so five years ago.
What’s about to be the next big thing is wide rims. Ibis recently released a wheelset with 41mm wide rims. Typically, a mountain bike rim is in the 20mm range, so this is a big change.