The F3-800 will be a larger version of the F3-675. The inline three cylinder  engine of the new bike should be the same with that of  Rivale and Brutale, although it is expected to be much more powerful than the 123 bhp/11600 rpm  and 8.3 kgm/8600 rpm  (60 ft lbs/8600rpm) nominal delivery of that engine. A 140 bhp figure is a fair guess.  This was also  the case with the F3-675 compared to Brutale 675.    
The frame and  electronics should be the same with the 675 version. The weight should be about the same also, 167 kg (368 lbs) nominal dry, while the price could be about  14000 Euros. 

Comment: The three cylinder engine layout as it has been successfully featured by Triumph in the last 20 years becomes a trend among the  manufacturers (MV-Agusta and Yamaha for the time being).