I dont think FFG will make a D3E, you only need to look at forums to see that is more profitable to exploit D2E and make new mechanics that make a new edition, because nobody will buy it. The base game works very good and Imperial Assault and Mansions of madness plays with similar rules as D2E.
As for what you are saying, I do not think there is a need for a new edition. You can create a new manual (Like the Heirs of Blood) with corrected mechanics, like so many other games (D2.5E). It would also be viable the option of a new campaign (either in physical format or in the RTL App) with your suggestions. An official PVP mode or a new campaign in which different characters you didn't choose at the begining are added in temporaly in different missions, to force you to play with them.