Hi USR, (btw, we use our real names here)
Hopefully, I'll be using tape for the rest of my life.
Unfortunately, my meager purchases won't make or break the producers of current tapes.
However, I aways advise folks to avoid iffy eBay purchases of old tape stock and support RMGI and ATR Magnetics in hopes that our combined purchases do make a difference.
There do seem to be more and more commercial, prerecorded tapes becoming available and while their appearance has just trickled in, they are and will be, in need of ample tape stock.
Just like the Tape Project, these new prerecorded tape offerings are premium products and I believe that the demand for them exists.
And just like the "manufacturing cost vicious circle" you mentioned, the more prerecorded tapes that become available, the more willing folks are to invest in the hardware for home playback and the more interesting the idea of producing prerecorded tapes becomes.