My guesses
Some form of LK93 or MK85 for states that have more restrictions on the ML seasons.
The 52cal is getting some more sabot attention, most likely just adding a 52x452 for more bullet selection....im pretty sure about this one.
52s are not going anywhere soon since you can now buy both the 52x458 and the 52x475 sabots...im sure because i bought both recently.
I doubt you will see a LRH AND Ultimate Slam or whatever they name it competing together. Next models down will likely be some kind of Elite or Extreme with a "twist".

Not quite a LRH since you want your flagship to really standout from the pack.
NFPJ ignition designs will be more BH209 friendly.
I doubt you will see any 45s unless they are special editions.
As far as the 52cal having a ballistics advantage, well it does IF you want to shoot the big .475 375gr Redhot with at least 120gr of powder. It can deliver a ton of energy at 100yards and over 3100fpe at the muzzle. The same bullet in a current 50x475 sabot from Harvester falls only about 200fpe shy and not quite as accurate. Using a better 50x475 sabot they might be closer. Using the 458s from either caliber, there is not much of a difference unless they are kinda heavy.