Stallone - hopefully more MCU stuff (Avengers 7 - Galactic storm?)
Arnie :
Jingle all the way : 2 many Grandpas. A comedy version of expendables. Arnie's character is laid off and widowed. He is determined to find a sold out hot toy for his grandchild, and so are scores of other seniors. Cameos by Stallone, Linda Hamilton, cast of predator etc.
Heidi's kick-ass grandpa. Commando type flick where sweet young Heidi has run afoul of some Andrew Tate types and must come to her rescue..
Terminator 2029 - Arnie as an aging robotics genius. Cyberdyne were going to use his designs in the 90's but they were lost in Sarah Connor's terrorist attack. In 2029 he creates amazing androids to serve in warzones. I was thinking of Jonathan majors as an African-American T800 but will need someone else now. Arnie has sentry units he is able to control in VR mode that fight with a rogue terminator..
ARNIE and Stallone : Grumpy old action men. Action parody with Stallone. Maybe a couple of retired action stars thwarting a cruise ship hijacking...
Voice work together for a heavily advertised Contra game (finally!)