I think that tesseract isn't really neccessary for RE. I'm satisfied enough by the actual engine. We should make the best out of the basis we have.
Think of diablo II for example: at the time when the game came out, blizzard cames up with an outdated engine, but with the artistic finesse and the vision of a great experience they built up a very successful game. They created an addictive concept and used all possible things in that simple engine, combined with nice artworks. The whole spirit inside decided over the success not the technical side. (Besides the money they had to make advertisement.)
(Abandoned games show also, that they still can make fun although their graphics are "outdated", if they had the "spirit". My examples: Bullfrogs "Magic carpet" and "Syndicate Wars"(DOS-BOX), Shinys "Sacrifice"(was not so successfull, but great), ... .
Technical outdated doesn't mean contentual our artistical outdated. All the Indygame productions (minecraft e.g.) proofe that. I could also see that in a video games museum, that we have in Berlin

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In our case means the cube 2 engine that more player can reach the online game. A fact that is an advantage no disadvantage.