The problem I see with 40 careers is that we have 4 very different starting races. They all have some unique careers that will not bend to other races. Slayers, wardancers etc. So if they intend to include any of the unique careers, and by pictures of Slayers i believe they do, this will narrow done the more generic careers even more.
This will propably mean that we will get careers bundled up, and we still will have very few of them. Which means that to get the 3rd ed mechanic actually work good, you need to buy at least the adventure kit with more careers (and unique action cards as said in the video.. *sigh*) and still be far behind the versatility of 2nd or 1st ed.
Question remains if they intend to hold on to advanced careers. If they do the careers might be even more narrowed down.
When we count Adventurers kit into, I'm pretty sure we have most of the careers from the MMO: ironbreaker, slayer, engineer, witch hunter, knight of the blazing sun, warrior priest, wizard, swordmaster, shadow warrior