Well yeah the underground scene is changing.
Most old school are more interested in being the security consultants, and you cannot very well release viruses in the open if you want to do that.
The other side is really in keeping the information locked up a little tighter, people will have to work for their 'leet hacker skillz' a bit more now, some places are removing the free content, and yeah some books are looking like they may make a banned list in the near future.
A virus is not just an infinite loop :) It really involves the way to automate propagation, avoid detection and avoid removal, and I know some will try to argue that is a worm but really they are one in the same, not much is to be gained from drawing a distinction.
Automated propagation is useful for software packagers, so add a 'Do you wish to install this?' and you are more on the road to legitimate software. Avoiding removal has it is uses, firewalls are one of them, systems that need to offer 24/7 service as well. Avoiding detection, well hmm there are some security paradigms that use it, and yeah actually I was going to say that was the only one not needed, but again some security tools do need it.
I always felt that perhaps AI would come from viruses, and yeah to a degree that has been proven right, they would still probably fail a Turing test, but they are alive in the sense they have mechanisms that pronounce the idea of survival.
Really it is down to the prison sentences that releasing a virus into the wild would accrue, that is the main reason the hobby side is dying down a bit. I am sure there are people out there willing to write a virus for a BJ and packet of pickled onion monster munch, but most will want some cash for doing it now, and as I mentioned before the skills are useful in a non illegal way also. It is just not worth it for hijinks anymore, that would be my guess.
And yes people do target botnets with viruses - what is interesting in the security field is any bright idea is often pursued, whereas conventional development things tend to be done by the numbers. I think that is the draw really for a lot of development to security, you are involved in an arms race that changes daily, and where breaking the rules literally means you are ahead of the competition.
Virus writing has not gone, it has just mutated into a more virile elitist form.