Reading Robert Frijns' twitter in the last few hours has proved how much he will be missed from GP2, best part of a dozen current drivers have posted their though on his seat-loss. A bit of a joke really as he's one of, if not, the best in GP2 at the moment.
And about replacing GP2 with something else, what exactly is out there?! Formula Renault 3.5?!
GP2 is the last level to F1 and has had many drivers promoted in the last few seasons: Maldonado, Perez, Grosjean, Kobayashi, Pic, Chilton, Bianchi, GVDG, Gutierrez Gutierrez...
Sure, some of those names are never going to be race winners let alone World Champions, but that's nearly half of the current grid from just the last four years.
Wanna go further back? 2008 GP2 season had Bruno Senna, Vitaly Petrov, Lucas Di Grassi, Karun Chandhok. 2006 had Lewis Hamilton and Timo Glock.
This shows that even if GP2 isn't full of talented individuals (just look at the names I've pulled out) it shows that there isn't really an alternative.