is there any plans for a 737-800 or 900?
At some point, maybe? Right now I don't know of any plans for that aircraft.
I'd like to see a 737-700 through 900 NG, too. Maybe even with the split scimitar winglets
In the mean time you have the old fashion dials and the 737-500 we have also offers quite a bit in terms of switch-able things. You should give it a try, it's still a very similar aircraft.
i been flying it and loving it