So my theory falls into the genre of cultural evolution. The existing theory of cultural evolution is the “meme theory,” that culture works like a virus. The big problem with this is that the more bits of culture look like viruses, the more it becomes the case that they ought to be pathogenic.
This isn't a "big problem" with any meme theory I am familiar with. In most memetic theories, cultural symbionts can be parasites, mutualists or commensuals - in their relationships with humans. Many have said this explicitly. I don't think there is a "parasite-only" version of "meme theory". The explicitly virus-oriented variants of memetics promoted by Richard Brodie ("Virus of the mind") and Ben Cullen ("Cultural virus theory") go out of their way to avoid this mistake.
What the old theory, the meme theory, would predict about the internet is that it allows the pathogens access to a much larger pool of potential victims, so things are just going to get worse for us. But in a domestication theory, what you would expect is that language would improve on the internet, that there would be lots of people coming up with new things and refining things.
I think this is a silly dichotomy. It is true that memetics predicts an increased density of humans will lead to a greater proportion of memes that are deleterious to the genes of human hosts. Indeed, we can see the effect of a high density of humans and a large concentration of memes today - simply by looking at Japan. Japanese have below-replacement fertility. Their DNA genes are suffering. However - as far as I know, many Japanese folk live happy and peaceful lives. Instead of saying that memetics predicts that "things are just going to get worse for us" it would be more accurate to say that memetics predicts that more of the world will start to resemble Japan - in having a combination of high meme densities and below-replacement fertility.
If you look at eusocial ants and bees, they live close together and have horizontally-transmitted pathogens - but they also have a variety of meticulous hygene practices which work to minimize the impact of their pathogens. It seems likely that humans will respond similarly to higher population densities and more horizontal meme transmission - by developing cultural anti-pathogen techniques and strategies. Just as hospitals, vaccinations and quarantine are used to defend against DNA-based parasites, so their cultural equivalents will be used to defend against hostile memes.
One interesting question for humans is whether these defenses will evolve rapidly enough - or whether we will wind up with an "ebola-like" situation - where the human hosts are treated like disposable resources to be converted into memes as quickly as possible. In standard epidemiology, it is rare for a disease to wipe out its host population. However, we know some of the factors that make this type of event more likely to happen. For example, if a parasite only has one host species, it is unlikely to exterminate it. In this model, we are probably OK so long as we are the primary hosts for memes. However intelligent machines look set to become another host environment for memes in the near future. When that happens, human hosts may need to take greater care. Another factor is generation time. Slow-reproducing and slow evolving hosts are more at risk. We probably don't score too well there either.
Memetics seems to be the practically the only theory of cultural evolution with practitioners who are interested in these issues. For example, Susan Blackmore recently testified that many cultural evolution practitioners had bought into Ed Wilson's dopey 'leash' model of cultural evolution - in which meme evolution is constrained to be subservient to to DNA gene evolution. It would certainly be dangerously naive to think that the world's memes have been successfully domesticated - and so everything is going to be OK.