I understand that tethering is a big concern/issue on these forums. But, I think the whole article isn't just about that.
I think it also deals with the fact that when we root and flash roms/kernels, we end up with phones that we can be relatively happy with well beyond the planned upgrade cycle that big name carriers are used to. Before the emergence of Android, most people signed a contract, and updated to the newest, sexiest looking phone as soon as they could (even the "crackberry" crowd). Now, people are still rocking their OG droids, well after the release date. Granted, yes our community is small in terms of the vast majority of Android users. But still using the same phone, when 4 years ago we would have upgraded as quickly as possible...that's hurting the carriers' pockets.
On the flip-side of people doing that, you have more and more "tech enthusiasts" signing up for 1-year contracts so that they can upgrade to the latest and greatest every 10-12 months, which does have potential to hit carriers hard, since they make almost all their money off of 2-year contracts, not the price of the phone.
What I think may happen, possibly far into the future, is Google becoming a carrier as well as a platform provider. This is all skeptical, of course, but if they truly wanted to stick to the "open-ended" side of things (while big carriers like Verizon and AT&T were crying about losing...lets face it...paltry sums of money from people not continuously upgrading) it might be one of the best moves they could do for the Android community.
I could, however, also know nothing and be completely wrong in this speculation.