Descriptivism and widespread misspelling

Personally, I feel that am not in a position to decide such things, so I gladly leave the decision to people whose whole job it is to make such decisions. When a respected authority known for its descriptivism (say, Merriam-Webster) starts listing "fuschia" as a legitimate alternative spelling, I will be more inclined to accept it myself.

Until then, I am heavily biased towards "fuchsia". (Even doubly so because I am one of those few people who actually pronounce it [ˈfʊksja] rather than [ˈfjuːʃə]. In other words, as far as I am personally concerned, I just can't misspell the "chs" as "sch"; if anything, I am likely to misspell the word as "fuxia".)

I think fuscia -> fuschia instead of fuchsia happens because Google is looking for better spelling fairly close to the misspelled word, and fuscia -> fuchsia is two mistakes, according to Google's algorithm (you've dropped the h and you've swapped the s and c), whereas fuscia -> fuschia is one mistake. At some point, Google may very well special-case fuchsia to fix this problem. In fact, this hypothesis is verified by experiment. If you search for "fucshia," Google corrects it properly. If you search for "fucsia," Google thinks you're speaking Spanish.

In general, misspellings or nonstandard grammar may become acceptable if they simplify things. So "thru" instead of "through" or "learned" instead of "learnt" work. This might apply in this case, but it's not very obvious.

But in this case there is the overriding principle that the name is derived from a proper name, because the plant was named after a guy named "Fuchs". And you need a much stronger case to change that.