I think there are, at this time, a couple options for dynamic marquees on regular LCDs.
You can hide most any kind of screen, if you put the marquee down in the cabaret area like Cube does.
You can run a big regular 16:9 LCD in portrait, use the bottom as the game screen and the top part for dynamic marquees via mame layout files or similar, optionally using cabinet design to disguise that it's all one screen, like some of the unused concepts for Blip did.
You can pocket the bottom part of a regular size screen as your marquee area, and stick the rest out the top of the cabinet like a topper, but that's kind of awkward looking. If you had low ceilings in your arcade and a tall cabinet, maybe you could hide it through the ceiling...
You can form a sort of T-joint, with your main screen laid back, resting against the midpoint of the marquee montior, and the top half of the marquee monitor exposed above it, if you don't mind that driving a kind of weird shape to your cabinet profile and a bit of an odd lean on the marquee - there was a bartop here that did that a while back and it worked pretty well.
It miiiight be possible to do something zany with mirrors, but I'm pretty sure it'd look weird. Similarly, it miiiight be possible to do something with a back-projection screen and a projector inside the machine, maybe bouncing off a mirror for throw length, but it's also going to be experimental and probably expensive territory.
Or you can shell out for a weird aspect ratio LCD panel for the marquee.
It's possible to cut LCD panels and have them still work afterward, but the equipment to do it or the shop costs of having it done are astronomical - that's actually the origin of most of the weird aspect ratio LCDs you see commercially. They did it in bulk, and the result is STILL spendy.