I am happy with the way they are already doing it:
A lot of new planes plus fixing some old planes as time permits. Seems fair to me. That way people bored with the old flight models get a taste of something new and people are dedicated to one type get to look forward to progress as well.
Seeing as how they redid the Spitfires when the Spit XIV was done, it seems practical to redo old types when variants are being done.
With the P-51 being the focus... is there an A-36/P-51A or P-51H coming soon? May the P-38 crowd will get a double whammy: new P-38s plus a reworked L model.
I am curious to see if the P-61 ever makes it to the planeset. I think, as Mitsu pointed out, there need to be a whole lot more Japanese aircraft done. I would also like to see some of the lesser known but significant aircraft like the French fighters, the biplanes, etc...
So much to do and such a small workforce. But that is good for HTC. It means they can earn a lot more money over a much longer time instead of finishing the game as quickly as possible and moving on the way most box sim developers work. What's good for HTC is good for me since I am generally very happy with their product and the direction it appears to be heading.