As far as i'm aware, Frostbite is EA's in house engine and they use it for all kind's of stuff, for years and years - highly unlikely they'll start using something entirely different all over sudden.
Also keep in mind today's Frostbite engine is not the same Frostbite it was in 2008 - Frostbite as well as other engines receive updates that add and change functionality quite a bit.
So if there's any "next iteration" of PGA Tour, it will be on Frostbite again - same Frostbite? Depends on when "next iteration" will be, but given PGA Tour being a live service game and as such does not qualify for yearly title releases, it would probably be a different iteration of Frostbite.
Thank for pointing out that Frostbite has many different iterations and updates. Another poster from another post has mentioned that Tiger Woods PGA Tour 14 was not using Frostbite. TW14 is one game I miss and I thought replacing Frostbite could replicate its gameplay and physics to come along with the current graphics. If an updated iteration of Frostbite could utilize the same features as TW14 and improved graphics, that would work well. I just changed the title as well.
