All i read was "friends" "friends" friends" "friends".
If that is the case then you should get them a PS4. Some of there friends may already have it or most of them will be getting it for xmas as you pointed out. N point buying a PS3 for them now unless you plan on buying them yet another console in a year or so from now. Just go with the PS4. By this time next year no one will be talking about a PS3. And if I know kids at all... having a PS4 will give them a lot of "cool points" in school. It sounds silly I know, but those things are important to kids lol.
As for what games they would play on the PS4 besides Fifa and minecraft, well it would be either Little big planet or racing games. There are a couple of other games (indie/retail) with comic violence or none at all like Journey, flower, The witness, Rime...etc that they maybe able to get into. As it stands I have your kids pegged at 7-10yrs old. They will grow with the console.
Get them the PS4. You may even enjoy it yourself :)
edit:
and pleae, ignore everyone telling you to get a PS3 cause its cheaper and has a bigger library. That kinda logic sounds more like being penny wise pound foolish to me. If you want cheap for the PS4 then wait and buy games used. But for the reasons you mention and for the games they seem to be into then buying the PS4 would be your best bet. So you get a PS3 and they play Fifa witheir friends this year. what happens come january when most of those friends have got a PS4 for xmas. And the rest of them are following suit through next year. Do you want your kids to be those guys that just picked up a PS3? Would you be willing to then spend money (again) to buy them the PS4? The advice most of those users are giving you, are things even they wouldn't do if they were in your shoes.
