There’s Eclair bakery on the UES in nyc, although the eclairs are rather pricey they have a wide variety of flavors
I think that as a trend/“thing” that eclairs won’t take off because they are very perishable and also take a level of pastry expertise that i feel is a different skill set from cupcakes (i can make cupcakes, eclairs? Doubtful.)
As an aside there were a number of locations of Beard Papas here for a few years but then most of them are also closed now, so if with the backing of a large those eclair and cream puff shops couldn’t survive i don’t know how a smaller independently owned one could…