The old settler units have been divided, into terrain enhancing workers, and city founding settlers. Workers will take 1 pop point to build.

Settlers will take 2 pop from your city to build. they say this is to discourage the ICS that is civ's answer to the RTS tank rush.

what are the problems we can forsee with this? can our vets forsee using ICS anyway?

I myself am kind of ticked off about having to take 2 heads from my city to found another city. will my new city start out with 2 heads?
HEY! Wait a minute! If new cities start out with 2 heads,and they eliminate the free square, then ICS is dead, and you still have the same basic starting conditions.

I started out hating the idea, now I've talked myself into loving it.

Its biggest effects, of course, will be in the early game, and this is indeed very welcome in one sense. But unless other areas are made to compensate, we could also be left a VERY slow early game...which might or might not be to people's liking. One good effect of the slower start, though, is the computer might have a much better chance early on, which has a potential host of good side-effects in and of itself.

By the mid- to late-game, however, you can expect people to be 'booming' (ICS-ing) as they always have with very little changes overall. So what if my size 18 city drops to 16 so I can start a new city? There's virtually no reason NOT to do so (unless there are other factors at work here we haven't been told). This might add just a bit more strategy as the WHEN to ICS, but the necessity to ICS (at least against a human player) is still with us.