Next up would be to make the “mark to market” tax retroactive to the date of purchase
It inherently is. It would be your basis at the end of the year, less the last basis you'd already reported. Yes, they could make it year to year.
Most likely, they would take the commodities market as a model. It hasn't been mentioned in the comments so far, but futures (i.e., the commodities market) are marked to market at the end of the year right now, and taxed at a blended rate that is 60% capital gains and 40% ordinary. It has to do with the fact that its easy to roll over contracts.
Anyway, I think the first focus would be financial assets. Of course, the next "tax expenditure" would be seen to be real estate appreciation. Imagine the corruption and bribes that would be associated with the assessor's valuation!
Exactly, so they get a good first bite at the apple.