Yes and no. 21700 seems to be a niche market. There are still a lot of 18650-only mods being put out. Not everyone wants a 21700 mod as they do usually tend to be a little larger. Some people who want their mods to be as small as possible and don't need a larger battery will still want 18650-only mods. I only mention if a charger takes 21700 or not because 21700 is popular enough among vapers to justify mentioning it. IMHO, if a person is in the market for a new charger, there's no reason to get a charger that won't fit a 21700 battery. Never know, you may just buy a 21700 mod someday. The cost difference between a charger that takes 21700 and one that doesn't is negligible if there is any cost difference at all.