The problem with your 2+2+2 design is that you are replacing an additional seat for an aisle (empty space). This may sound good but it also represents a 14% reduction in potential revenue for an airline (not a good thing).
The bigger planes have twin aisle due to the greater seat number 2+4+2 or 3+3+3 or even 2+5+2. I am sure some bean counter may be salivating at the option of a 5+5 configuration somewhere.
The sucessor for the planes you mentioned are the twin aisled 787/350 and the 330/777 designs. The short haul routes are most economicaly covered by single aisle (737/32x) designs.
A narow body business+ configuration may make economic sense, but you need the larger size to make money with economy passengers.