I wonder if a hybrid approach between disposable and "keep cup" could work.
The "default" takeaway option could be the short-lasting paper cup.
For car, office or just comfort, you could have a squashy, silicone (stands high temp) outer that would usually only need to be cleaned if the inner cup fails.
A silicone shell with disposable inner would work well for me, at least. The shell would rarely need to be cleaned and can be easily pocketed.
The "default" takeaway option could be the short-lasting paper cup.
For car, office or just comfort, you could have a squashy, silicone (stands high temp) outer that would usually only need to be cleaned if the inner cup fails.
A silicone shell with disposable inner would work well for me, at least. The shell would rarely need to be cleaned and can be easily pocketed.