I think a fair bit also depends on how the siloviki view Putins progress, I mean in terms of world power Putin has brought Russia back into the forefront and kept it there, people view Russia with more respect now than they did back in the early 2000s when it was the laughing stock of much of the world.
Unfortunately he did it by riding on the back of the dollar value of oil which has subsided a fair bit, however it's a fairly sure bet that this is only a temporary lull in value and that it will go back up again, especially if Saudi Arabia loses the war. Whatever replaces the Saud government might not be particularly friendly to western interests, in fact it's very likely not to be since it will view the west as propping up the corrupt Sauds. Obamas move to try and ease relations with Iran and back off a bit from Saudi Arabia might help a bit there, but there's a lot of history between the US and Saudi Arabia so that's not something that can be just swept under the rug.
I think Putin isn't in any major danger of losing his position yet, he's got himself into a good spot, his main opponents have either mysteriously died or have gone quiet, so he's relatively stable.
Of course, like the old days, you never see the knife that gets you, because it usually comes from behind and into your back. Putin is KGB (You can't say ex-KGB because it's like the Marines, once you're one, you're always one) so he knows to watch his back, he wouldn't have made it this far in Russian politics if he didn't.
Come to think of it, if Putin does run again in the next presidentials then he'll have run Russia longer than any leader since the end of the Tsars.
