Can there be a way to buy gold membership subscriptions from the zen store?
I think there may be a language barrier issue here, I'm not sure whether you're asking a question "can I use my Zen today to buy a gold sub?" or providing feedback "Cryptic, please add a way for me to buy a sub with my Zen".
If you're asking the question, no, it's not possible today, nor have they advertised any plans to make it so any time soon.
If you're requesting that they do so, I agree; they should. Or rather, I think they should abandon the sub model altogether, and move to the pure F2P model that Neverwinter is going to have. Give all us lifers a big chunk of stuff to make up for loss of the stipend, and move on.