Removing CD from the equation eliminates half the reason I would want something on PCE in the first place. %90 of what can be done on PCE with only a HuCard can be done just as well or better on SNES or Genesis.
Redbook and ADPCM are all that matters?
If music were all that mattered I'd just have a CD player instead of a Duo. Obviously they are not "all that matters".
I suppose that what you were getting at is that everything a CD can do a HuCard can do providing the HuCard is big enough, and therefore I guess I guess some clarification is needed for this fantasy. In the real world SNES and Genesis carts eventually exceeded the size of even the largest HuCard on a regular basis. The largest SNES cart is literally double the size of the largest HuCard. So while Dracula X with shitty music and no other downside is technically possible on a HuCard, it never would have happened. Most of them are 4 or 8 Mb, which makes things like Comic Zone, Clay Fighter, Phantasy Star IV, etc impossible without a NES-grade conversion.
By the time the SNES and Genesis were going strong the main draw of the PCE was CD. The SNES was better at everything that didn't need clock speed, and the Genesis killed them both in that territory. When I think of "dream ports" I think of things like "A CD version of Final Fantasy, Seiken Densetsu, Super Robot Wars, etc" not "Something like Game X but with no scaling and lower spec music".
If we are talking about unlimited cart size, something that would have cost hundreds of dollars in cart manufaturing alone in the early 90s, then I guess I'll take Pulstar or Marvel Super Heroes versus Street Fighter.
On a more realistic note, I guess I would like to have seen some good arcade ports of games that only showed up as crappy NES hack jobs, Rygar, the first two Ikari games, Ninja Gaiden, Turtles.
What I really want though? A LDROM2 version of Dragon's Lair 1&2. Big time.