New edition in the book-publishing sense (different typesetting, pagination, art, etc.)? Yes, obviously.
New edition in the idiosyncratic way that RPG players mean, where a new edition is a new version of a game's base ruleset? No, not in the way that WotC has used the term "edition" historically. (The argument could be made that the leap is similar to that between AD&D 1st Ed. and 2nd Ed., but I'm not sure if TSR's usage is relevant here.)
WotC has never changed edition numbers without also creating a whole new incompatible game system, with entirely different XP advancement tables, saving throw mechanics, attack roll calculations, spellcasting mechanics, etc. This new 5.5 edition is . . . clearly not that relative to 5.0. In fact, the change from 3.0 to 3.5 is a pretty apt analogy.