I'm interested in seeing these characters brought into the 21st century. The question is: How?

In all honesty, I can't see Hasbro producing non-transforming components, IE shells. But I think a clue about how they could approach it lies in the current Titans Return Titan Masters.

The Headmaster transforms from Head to Robot, and comes with an accessory of its own -- a vehicle or beast. Said vehicle or beast transforms into a weapon, but can also combine with the Headmaster to create a larger vehicle or beast. It's a marvel of engineering.

Take the example of Clobber: Grimlock's head combines with a dragon to form a little T-Rex. When the (presumably) eventual larger Grimlock body is released for this head to call home, you've essentially got a toy that's doubling-down on the T-Rex mode as both the larger toy and smaller components transform into dinosaurs.

Now, apply a similar kind of thinking to characters like the Pretender Beasts: A robot transforms into a beast which hides inside a larger version of the same beast. Catilla, for example, is a saber-tooth tiger inside a saber-tooth tiger. You're doubling-down on the same kind of beast.

The wonderful thing about the Pretender Beasts is that the originals came with accessories -- helmets and blasters that plugged into the shell. What if Hasbro took a character like Catilla, made it an organic saber-tooth tiger which had accessories plugged into it (like the original shell), that could transform into a robot and said accessories could combine and transform into a smaller saber-tooth tiger.

This does away with the potentially troublesome shells altogether.

Am I making sense?