What if the "next movie" is all three?
Get some guys in suits that are based off the 90 movie, CGI Shrekurtles and then a new nice combination of both in a live Action Turtles Forever.
Start in Dimension X with the OOTS Krang having the Shrekurtles somehow get there but doing so kind of rips the fabric of space time. Then have the Shrekurtles somehow, for some unexplained reason bring the 1990 Turtles into it but this, for some unexplained reason sucks the "new" Turtles into things first... then commence with movie. Shrekurtles die, 1990 movie turtles go home and then we follow this new style Turtles into a new trilogy. Everyones happy.
