The way to future proof is a conduit, so that you can pull through whatever gets invented in 20 or years time and your cat 6 is obsolete.

Trying to second guess that cat 6A might be able to support some 25GB future standard is a fools errand. In the OPs situation, install cat 6 in conduit and if you need to pull through something else in 20 years it'll be an easy job.