As ICE cars are right now, no, because unlike electric engines, combustion engines and the clutch can't be made efficient, cheap and compact all at once.

If you have to end up with 4 "normal sized engines" or "normal sized clutches" to implement this, you now are in net gain of wasted weight/space.

The HUB takes up all of the space where you disk or drum brakes would be. ICE cars don't benefit from regenerative braking so you'd have to come up with another solution of how to stop the car.

Inboard brakes exist in specialty applications such as F1 and vehicles with portal axels like the Humvee.

Probably not, this is using four motors that are close to each wheel. ICE cars route energy from a central motor.

can this not use a single center motor with a shaft, just replacing the current structures? It won't be that big savings as it is in electric vehicles, but it could reduce some complexity and unify architecture of electric and ICE?

This proposed power transfer mechanic linkage can't handle angular differences between the power plant and wheel, so you would end up with broken mechanic linkages and torn shafts.

Non-spinning-shaft power transmission (doesn't really need to be electric, could as well be something like fluid power transmission like hydraulic or pneumatic power) dodge this by putting the power plant in a way the angle between power plant and wheel can't change.

If you have a single central motor and shaft, then existing CV joints work just fine. This is useful when you want to have a separate motor for each wheel, because it lets you put those motors closer to the wheel. There is then space in the middle (where the shafts went with the single central engine/motor) that can be used for something else not related to the drive train.

Not really. You can use this on an ICE, but this really is useful (compared to a CV joint) when you have very short axles. On a ICE the axle needs to cross the entire width of the car anyway in some form, so you may as well use a CV joint. With an EV they want to use 4 small motors as close to each wheel as possible and thus free up space in the middle of the car where the axle used to go. A CV joint has a longer minimum length axle compared to this, so the motor has to go that much closer to the middle. When they use this they get useful space in the middle of the car (between the motors) that can be used for something else.