When we break it down like that, it certainly looks realistic as long as nothing changes in the tennis landscape. Wins at Rome and RG would put him well clear at the top of the Race, and he could use that buffer to his advantage for the rest of the season. So again, working on the assumption that the NextGen stay as they are and Djokovic/Murray have a down year, the other contender is, of course, Federer - and he's still a bit of an unknown as we don't know exactly which events he'll play.
I'll try and break down what I think a realistic set of results could be for him and then cross-compare:
Currently on 4,045 points.
RG - QF - 4,405
Halle - W - 4,905
Wimbledon - W - 6,905
Cincinnati - W - 7,905
US Open - SF - 8,625
Shanghai - QF - 8,985
Basel - W - 9,485
Paris - R3 - 9,575
This is a mixture of optimistic and pessimistic results based on whatever I've seen from him in the first 3-4 months of the year and also assumes that he skips Montreal and Stuttgart. If he meets his goals for the year, it would be pretty much neck-and-neck between these two heading into the WTF (at which point whoever performs better in London takes it). A lot is going to depend on how important the No. 1 is for both Nadal and Federer as a goal for the year - is it worth playing a normal schedule to get the points? I think Federer skipping almost the whole clay season is actually a big factor in this (if he had played MC, Madrid and Rome and reached maybe 2 QFs and 1 SF, he'd have an extra 720 points which probably tips in his favour).
Next step: a key assumption I made in the quick projection above is that the two pretty much avoid meeting each other for the rest of the year, which probably won't happen. They may be drawn to meet in a couple of QFs in the next 2 months, but after that their entry rankings should be high enough to make sure they don't meet till the Semis/Finals. We would need to see how big a role this plays in the allocation of points across the big tournaments
Finally, lets deal with external factors:
- what happens if Djokovic gets back into form?
- what happens if Murray gets back to his best?
- what happens if they both get back into form?
- what if the Young Guns step up?
All sorts of things could happen here, but if either one of Djokovic or Murray hits a purple patch, they could potentially regain all this lost ground and still end as Number 1 with a surge of consecutive tournament wins (more likely with Djokovic tbh). I would assume that Djokovic getting back into form might impact Nadal a little more, but again this would all depend on how the tournament draws pan out.
So I think the bottom line is this AT THE MOMENT: if Federer bags another Slam, I would back him to finish No. 1 as he should be able to pad his total points tally with respectable appearances at other tournaments. Otherwise, I would favour Rafa with the caveat that no-one else spoils the party.