some ideas

1. A foreign players list including possibly the top 20 players outside the nba that are over the draft age or went undrafted at the time. This would apply especially for dinasty mode and the best players should change as the dinasty goes on (retiment and some players going old and others improving) but at the start the originals should be there (scola, vujanic, etc..) .

2. D-League, not playable but simmed. During the dinasty mode teams would have the option to send or get back 2 of their rookies or players with one year pro and there should be a section that display the results. Moreover if the players have good games they should be rewards with an increase on their stats, nothing big but a bit.

3. Trade Negociations, in season and off-season (Dinasty Mode). When a team receives an offer they should be able to send a counter offer in which they casn ask for or a replacement or an addition.

1. Not unfeasible I guess, but difficult due to licensing issues.

2. That'd be pretty cool and probably feasible to implement with a similar interface to free agency. Teams would of course be restricted to their D-League affiliate.

3. Definitely. I'd also add that it should take place in "real time", so even though you might have to advance a day to make the trade official you could work it out without a series of PDA messages over a few days. And the Cancel/Confirm trade feature, so you can propose a couple of possibilities before going through with a deal.

Also 3-teams deals should be available. I don't why they ever took it away.
And trading future draft picks.

A lot of people complained about the three team trade interface because you couldn't trade between the CPU teams which limited its effectiveness at times. Personally, I was able to use it on occasion and would love to see it back, too.