I expect that the more common types of incandescent flashlight bulbs will still be manufactured in several decades time.
Production of the more obscure types has probably already ceased, though existing stock can still be found.
Uncommon types, as examples.
5 volt 0.09 amp E10, still manufactured I think.
5 volt 0.09 amp BA9S, production ceased only recently, still available.
5 volt 0.09 amp, P13.5 base, production ceased, no longer readily available.
2.5 volt, 0.06 amp, E10, still manufactured, possibly to order, min 100 pieces.
2.5 volt, 0.25 amp, E10 flat topped with opal back. No longer manufactured, hard to find.
As above but in red or daylight blue, almost unobtainable.
2.7 volt, 0.15 amp, PR base. Hard to find.
5.5 volt, 0.3 amp E10 base. Ever Ready ceased production, alternatives hard to find and of very poor quality.
Any type of flashlight bulb with natural colored glass, almost unobtainable.
None of the above were ever very popular.
There is still significant demand for incandescent pilot lamps and the more popular types are still made. A factory that makes incandescent pilot lamps should be able to make flashlight bulbs as the technology is very similar.
Incandescent lighting is going the way of oil lamps and gas lighting, both of which are still used today but neither of which are mainstream light sources for everyday lighting of homes and workplaces.
I can remember when a local hardware shop sold gas mantles, oil lamp wicks, and replacement glasses for gas and oil lamps.