Seems like there's a chance that "Avengers" as a franchise would hold both of those records. Depending on if the Avatar films continue to show diminishing returns with future instalments. Obviously that's impossible to tell right now.
Also, I should note that I don't know what the rules are here on considering individual franchises under the MCU as qualifying as "a franchise". I know that Box Office Mojo counts MCU as a whole as a franchise, as well as each franchise therein (Captain America, Iron Man, etc.)