Seriously though, it is not impossible to imagine an ASL expansion involving riverine patrol boats as used along the lower Danube and into the Black and Crimea Seas. This could include S-boats and similar which were employed in the low countries and in the Baltic. (There are already plenty of river mapboards.) Also, AFV carrying ferry boats, like used at Remagen. There were boats in the Volga at Stalingrad... and canal boats in Berlin. Maybe others.
We have had rules for rafts (E6.41) for decades now - but no counters!? Why? Some kind of an economy measure?! There might be new raft ideas - large enough to carry SW or more. (Or is all this already in the Dinant HASL?) If so, no matter it might be offered at little effort in an armed boats expansion. Such an expansion could also cover bridges in a bit more detail. Now we have only wooden, stone, and pontoon. Would be difficult to do a Remagen bridge HASL properly without new rules.
The above might (but probably should not be) combined with an expansion of small boats in the Pacific and China: PT boats, and boats smaller and even up to a bit larger. Seen in plenty of places on rivers in China, and in the south Pacific.
That's maybe two modules there. These two, or another module, might add a few unusual or specific aircraft and glider types to the mix. Searchlights. The timber poles erected to defend against glider landings at Normandy. New types of pillboxes, bunkers, and related prepared defenses as were used by the Russians and by Partisans in the early years of Barbarrosa. All with new counters and artwork.
So that's maybe up to three product ideas there.
Did anyone ask if TotR will include armored, and armed, trains? Someone is working on that idea, reportedly.
"Planes, Trains, and Automobiles (I mean, Boats)" On the other hand, what the heck? Throw some Civilian-style vehicles in there too.