Some reasons why IMHO Orkut wouldn't kill forums:
1. The power of niche - Orkut has communities on everything, but the apps they create will be one-size-fits-all. Forums like Pagalguy cater to niches, whether it's education, tech, mobile phones and thus have a much better sense of their users' needs than Orkut would. That helps forums make customized apps... Pagalguy has attempted something like that and PG Connect was a box office hit. It would not be possible for Orkut to cater to the hundreds of niches like that.
2. Orkut is largely a young people rage and it's not even the largest social networking site in the world, except in Brazil India Iran and a few more. In any case the new generation of users in India are going to Facebook and not Orkut. Websites are usually successful when they focus on one thing and then work on it. Orkut right now has positioned itself as a fun site to make friends and increase your social circle. Either it should focus on that or become a user-generated content site with powerful forums. If it goes forums way, it will lose the fun lukkha hangout feel to it. Attempting both is like axing one's own foot.
3. As for Pagalguy having the profile system, it's actually a vBulletin project only. vBulletin, which powers most forums across the world including this one, is about to release a full-fledged version with blogs and social profiles anyway so all forums in the world will automatically get upgraded to that. As for the utility, people anyway had their own social networks within Pagalguy and all we did was formalize it technically by adding the profile plugin. It does look like a social networking site - not necessarily Orkut but any - and that's for the simple reason that such a format has proven to be successful. It's a different issue that we've not pushed it to users aggressively so few people know that it exists... there are other reasons for it, related to what's coming in PG in the next year. I would say, if a forum has already grown into a 'community', it's a great idea to let people have enhanced profiles and public friends lists to support the forum and not necessarily to pretend to be an Orkut. At the end of the day, if Orkut is trying to be a forum, why can't forums try to be like Orkut
The obstacles for forums are -
1. No sense of content aggregation. The search isn't anything to wrote home about, precious content that is not replied to gets lost in the depths of the forum (also in Pagalguy) and hence it's often tough to reach the best resources of the forum.
2. Not all forums are moneymaking. Many of them are personal projects funded by a couple of enthusiastic guys or a university department. This makes it tough for them to develop niche features and products.
3. Forums and the development community that writes code for forums is too geeky by nature. As a result, there aren't many skins, pluging etc that the masses can be comfortable with. Which is why even in India, most forums are populated with engineering/tech crowd.
In the whole, everyone will survive... it's ok, it's all good