Forever is a long time. That said...my experience with frozen when new/first purchased and stored unopened, you are probably safe for 8-10 years, but it can still vary based on manufacturer and type. Somebody here may have more experience with longer time frames.
Today, I strongly believe that Kentmere/Ilford papers purchased new in 2016 would likely meet that challenge and be good in 2026.
All others are suspect -- just my opinion -- it's all about quality product and consistency in manufacture.
In my experience, paper as it age loses it's original contrast to varying degree and/or the base changes from white to pale grey. This effect varies by manufacturer and type of paper. Sometimes the grey can be avoided with additives to paper developer like a Benzotriazole solution.
I have been using several types of old stock bayrta type silver based paper that have been frozen for 5-8 years or more with good results. So far, 21st century made Kodak Polymax Fine Art, and Zone VI VCII that are still fine.
Unopened 10 year old Agfa MCC110 looks great. Kodak Elite, from late 1996 is loosing some of it's zip as a Grade 3..
Some of the original mid 90's Zone VI Brilliant graded paper is great, but turning flat quickly. Grade 3 is a grade 2, and the Grade2 is 1ish at best.