The new Sim City changes are all about heavily pushing users towards social multiuser play. The small city size means multiple cities are needed to do the big stuff and each city affects others, but one person can only edit each city in turn rather than concurrently. So you ideally need multiple players in a region to work it dynamically. Plus, this has the added goal of encouraging DLC purchases as other players will see what new stuff you've bought for your city.
I don't really have a theoretical problem with any of that in an abstract sense. It's a popular & potentially lucrative business model. But on a personal level, it feels a little too much like I'd be the Sim being nudged to behave in certain ways, rather than the person running the city.
I think a lot of older SimCity players probably feel that way. I was only a casual player because after a while, I just got bored managing everything. But a lot of SimCity fans enjoyed the game precisely because it let them feel like they were in complete charge of this vast ecosystem, rather than someone being pushed around in a certain direction.
So aspects of the new SimCity will probably not appeal to them. But they will probably appeal to a whole different tranche of people, so I still expect very good sales figures.
In fact, the last thing I'd be worried about with the always on connection is the game's servers being turned off; they'll want to sell DLC and other expansions on a title like this for as long as there are enough gamers are playing it. If need be, they'll reduce the number of servers but as long as there's a critical mass, they'll keep pumping out DLC for at least 5 years or so, probably 10. I wouldn't even necessarily expect a new SimCity any time soon. Instead they'll probably pump out various large-scale expansions of this game, like what happens with various MMOs. Vanilla will still be played, but on a shrinking number of regions, as new major expansions come out over the years to come. If it doesn't sell well at the start, sure, yes, EA have historically been swift to shut servers. But on a title like this, I don't think the sales figures will disappoint, so they'll want to milk it for as long as possible.
Whether you buy this game is more about whether its mindset jives with the kind of game environment you want to play within. It's not my cup of tea, personally. But if you're like me, it's not like there aren't already perfectly good SimCity games out there.
EDIT: currently watching JP McDaniel & Day9 on Twitch TV, attempting to play SimCity. Multiple difficulties logging in, then keeps crashing, kicking them to desktop; trololololol. It's kind of funny.