According to information passed to dealers this week, the only hope of more power in the 159/Brera series is to apply MultiAir and twin turbo technology to the 1750 which should result in power outputs of 235/265 - and possibly a bit more (rumours of "approaching 300 bhp").
Beyond that, there is likely to be a new platform for the "169" which may use the 3.6 Chrysler engine, and Giulia in 2012 ish. There is reported to be a 3 litre V6 diesel MultiAir in final development, which will also be in the 169.
Not much information about the future path of Alfa Romeo, possibly because Mr Marchionne is not convinced at the moment that it HAS a future. Lets hope he is proved wrong.