* The city would completely control my access to rights of way and pole attachments, and would be motivated to keep me from getting that access or make it expensive;
So, exactly the way it is right now, except right now they do it at the behest of lobbyists, rather than their own interest. No change, from your perspective.
* The city would engage in horizontal monopoly leverage from its other monopoly businesses (trash, water, sewer, and in many places energy) and would enjoy cross-subsidies from them; for example, it wouldn't have to build a new billing system but could use its existing one;
While true, just how much did setting up and running your billing system cost you? Not much I bet, especially compared to the labor required to install hardware.
* The city could also use its ability to tax, and bonding authority, to obtain capital for the buildout at bargain rates;
Yeah, that's a bummer.
* The city, with its deep pockets and by expending some of that capital, could engage in predatory pricing, offering its service below cost due to taxpayer subsidies. It could do this at the outset, to take customers away, or possibly permanently;
I'll stop with the point by point here, because many of these points can be rolled together.
It very much depends on the model the city uses to "be an ISP." The Swedish model seems to work extraordinarily well. The city isn't really an ISP, in that case. They own (read, install and maintain) the wires/fiber that reaches individual subscribers, bring the other end into a building, and say "have at it" to people like you, who then offer the actual Internet service. You run the billing still, you run the routing and traffic shaping, and you arrange for and pay for the uplink to the Internet at large. You pay the city some fixed amount per subscriber, but set your own rates.
That's the model any of us who are paying attention would like to see. It provides all the room in the world for competition, while solving the natural monopoly/conflict of interest problems in the last mile. It allows competitors to differentiate themselves as much as they like. The city provides a dumb pipe. The ISP provide services through that pipe. Don't want IP TV? Pick an ISP that doesn't provide it. Want IP telephony? Pick an IP that provides it. Want a really cheap, slow connection? Pick the ISP that pays for a tiny uplink to save money. Sure the last mile fiber will be radically underutilized, but Grandma Jones doesn't use Skype video, so she doesn't care as long as her Facebook games work. (Though I suspect the old Grandma Jones stereotype is fading fast. She wants to be able to see the grandbaby, and Skype and Facetime are making it easier and easier.)
Will there be cities that provide the whole service? Probably so. In that case, yeah, you won't be competing. No one will. That leaves a monopoly provider, but in this case it's a monopoly provider that doesn't have a major profit motive, and does have to answer to votes quite regularly. They're not as unaccountable as you make out. In time, those votes may result in changes. It's quite possible that cities that initially build themselves out as the ISP will transition to the Swedish model, just to avoid the hassle.
This ruling will allow cities to actually try. We'll see how it plays out.