In the next few months? Zero. This year, there's the Compute Module 3, and the Pi 3A. Eben Upton said not to expect a Pi4 anytime soon.
The bcm2835 (in the Pi1) was chosen for convenience, because of the connections the developers had, and price. The 2836 and 2837 worked out because they were close to drop-in replacements, so when the chip costs came down enough to be affordable, the modifications were relatively minor. To move forward, they'll need to redesign the next board, and at the very least choose a different chip family that includes real USB host hardware.
I guess that's good and bad news. I would have liked a Pi 4 soon (the pattern seems to be new releases in February), but as far as I've seen it's probably good if they redesign the next version and use something more standard and modern. I guess they're still committed to Broadcomm though.
Maybe one of the chinese competitors is a better choice at the moment? I would like an Intel Atom based board, but that doesn't seem viable yet. Maybe they're too expensive, despite Aliexpress and other shops having lots of different Atom based tablets for not even double what a Pi costs.
If I recall correctly, the 2836 and 2837 were specifically designed for the Pi so they could be as close as possible to the original. Also, Eben Upton always insists that the next model isn't coming any time soon right up until the launch announcement.
The bcm2835 (in the Pi1) was chosen for convenience, because of the connections the developers had, and price. The 2836 and 2837 worked out because they were close to drop-in replacements, so when the chip costs came down enough to be affordable, the modifications were relatively minor. To move forward, they'll need to redesign the next board, and at the very least choose a different chip family that includes real USB host hardware.