In theory they will because it's mentioned in their Future Plans statement, tucked away in the "Other" section.
In this blog, we discuss some of the future plans for the game.
store.steampowered.com
"Of course, we will also be working on maintaining, balancing and improving all of the existing singleplayer features and content. This is including further AI fixes and improvements, for sieges in particular, as well as, a continued effort to improve performance across the board. This extends to the polishing of any newly introduced content, such as War & Peace reasons, and balancing existing mechanics like Birth & Death rates, skill experience gains, and armour effectiveness."
Yeah needing horses for upgrades but not equipment is a little strange. However I don't think it would be fun to have to source all equipment for troops as well. I would have preferred that troops didn't need horses to level up at all and it was just a part of their upgrade cost. But, these things are ultimately pretty minor.