My initial thoughts to that are:
1) Great idea. Bts should be shares of the DEX and not traded to external exchanges and only trade the bitassets. Great idea! It should have been like that from the start and if I remember correctly Tonyk was saying these things a long time ago and was ignored..
2) Unfortunately, like it or not, stable coins like bitusd don't have much demand yet. In total there are c$1.5 mil tether, c$800k Nubits etc.. So in a best case sceanrio there would be $1 mil bitusd and maybe some other bit assets which will make bts a market cap of c$3-$4 mil and will stay at those levels for another year..
The current market cap of bts is mostly based on traders speculation, on pumps and dumps like all the other crypto out there and on the expectation that maybe a big whale will jump in and lock a lot of collateral to create bitassets and bts will skyrocket to market cap. Not much of utility yet, but things were starting to progress (ccedk, kencode POS, stealth are things that will bring utility) so I am not sure this is the right time to go with a proposal like the OP.
Having said that if the OP is implemented then it will be more likely that whales will come on board and create those bitassets...So I don't know how I should feel about implementing this change...Please whatever you decide don't create a shock in the market and bts drops to $3 mil market cap because then my wife will divorce me..