Trading Horses for PP?

[joerock22]

Playing as the British, and watching my store of horses rise to 999 gave me an idea. Why can't we trade horses in for pp? In reality, countries could definitely sell the excess of a certain resource for money or exchange it for another resource. It definitely shouldn't be a 1:1 trade. Maybe 2:1, 3:1, or even 5:1. The concern is that players will just abandon cavalry altogether, but I'm tempted to do that anyway. The only thing that horses are really useful for is horse artillery, and you do need horses for those. I'm curious to see what people think of this.