Future of 3 series:
during the refresh in 2 years this will happen:
320i, competing with base Audi A4, it will get more power, around 210
328i, to compete with the Audi 3.0T, but with better fuel effeciency, they will raise the power to about 260HP (on paper, probably 280 in real life) so it competes with the larger Audi engine performance wise, the i4 is capable of this
the 335i will be gone
M340i (or whatever they call it, maybe still M335i) will compete with the S4, it will be more unique because there will be no regular 340i, and tons of BMW buyers care greatly about the badge on their vehicle and don't simply want an M in front of the same numbers the masses have if they are paying $10K more. The M340i will use the i6 (same as new M3) but with smaller turbos and around 350 horsepower, compete price and performance wise with the S4.
Then the RS4 and M3 will compete as they do now (well the US won't have an RS4 but you get the point)
This will also allow for greater engine (performance) gaps between the models and price gaps as well, 320 to 328 will add ~50 HP, 328 to M340 will add almost 100 HP and M340 to M3 will add around 70 HP