The Ahnold movies didn't move the needle. The REH stories would make a great foundation, and for that matter, some of the 1970s reboot stories (Carter, Sprague de Camp, etc) would make a great path for a preplanned series of annual summer blockbusters. They'd just have to be careful with the casting, pick someone young enough and good enough, but not someone who will play hard to get later. Or maybe just intentionally recast the lead role for each movie, make that part of the publicity. There have been something like six James Bonds, for example.
It seems the big weak point, in my view, is the screenwriting. Maybe they have to dumb it down for the average movie goer but I can’t sit through all the drivel when the abandon the original story plot to expound on some goofy, politically correct tangent.
Game of Thrones managed to get past this for HBO. Lord of the Rings managed to keep much of the original storyline, until The Hobbit, anyway.