Regarding the number of wallets, does it take into consideration people having multiple wallets? As BTC becomes more mainstream will the amount of wallets per user increase?
A quadratic model will be very accurate, I think. An a*t^2 term for nonce wallets resulting from network size, a b*t term for dynamic wallets, and a constant term c for static wallets. a is very very small now and can be ignored, unless apps arise which inflate it. b dominates over time, currently.