I can't imagine Ram will not follow Ford and GM by offering a large displacement, cast iron block, pushrod V8 engine in their lineup.
Ford recently introduced the 7.3 and 6.8 Gas engines, and GM is supposedly working on an all new large displacement offering for their pickups.
I know Cummins is working on a gasoline version of their 6.7 I6, but that's going to be turbo charged, and likely very expensive compared to an in house V8 offering.
When the old Chrysler Corp was going down the tubes in the late 1970's they jettisoned their RV and school bus chassis offerings. The end of the big block motors also brought the end of the higher GVW trucks. The Big Horn and COE diesel tractors were gone by then. The D/W 350 were the heaviest GVW models offered after 1980 with the exception of a higher GVW model series offered in Latin America.
As Lee Iacocca took the reigns, meetings were held discussing exiting the truck business entirely. Pickup truck sales fell off a cliff in calendar year 1979 because of a spike in energy prices and new tighter emissions regulations hurt performance and drove up prices. Plants were shuttered which meant the club cabs and crew cabs were no longer offered by the mid-1980's. What would become the Dakota was on the drawing board at that time, because a decision was made to continue trucks and vans. That decision also led to the Cummins relationship.
Today the heaviest payload model offered by Ram is the 5500 chassis-cab. Ford still offers the F-750, E-series cutaways, commercial van and motor home chassis. Ford has a business case for their 7.3 gas V8. I don't see the 6.8 offered in the HD trucks for the 2024 model year on the Ford website.
I doubt there is a business case for a new gas V8 to replace the 6.4. Most likely the 5.7 and 6.4 Hemis will continue to be built in small numbers in Mexico for the commercial vehicle market in Latin America. Some 6.4 engines will be sent here for the HD trucks. By that time the 6-speed transmissions will be gone, most likely replaced by the ZF Powerline 8-speed for both gas and diesel Ram heavy-duty commercial trucks.