He now has an unparalleled 9 consecutive years with at least 1 Grand Slam victory (incidentally he also holds a similar unmatched record for 9 consecutive years winning a Masters Series/1000 Series title), and not many would bet on 2014 breaking that streak.
It doesn't take an expert tennis analyst (luckily for me) to recognise that the main thing standing in Rafa's way is likely to be his own fitness. Over the last 5 years or so, he has been decidedly held back by recurring injuries, and in particular tendonitis in his knees. The chances of him being fully fit for all of the slams over the next 2 or 3 years seem slim at best.
If there was less competition then he might be able to cruise to the odd title but with Murray and Djokovic (as well as the likes of JMDP, Wawrinka, Berdych, even Federer) around, he will have to be at his best to win a Slam. Even then it might not be enough.
There has been lots of talk about this being one of the best years in tennis history but just a couple of months ago he was knocked out of Wimbledon in the first round. Then, all of the discussion was about Nadal's knees and his ability to play on surfaces other than clay.
At most he is likely to have 3 years left at the very top, before the physical nature of his play restricts his chances of claiming the biggest prizes, even on clay. That means potentially just 12 more chances. Can he win 5 of them to enhance his claim to be considered the greatest ever? Only time will tell.
Geeky statto alert:
It is interesting (I appreciate this is a subjective term) to look at the ages of Grand Slam winners. The below graph shows the progression in terms of slam victories for each of the best known major winners.
You should be able to click on the graph to open it up and see more, but here are a few highlights that I thought were interesting.
1) Aged 27, only Federer had more Slams than Rafa.
2) At 25 years old, Federer and Borg had 11 Slams, Sampras and Rafa 10. Borg retired without winning another, Pistol Pete kept going for years longer and added a consistent 1 per year, and then another aged 31.
3) Djokovic is considered one of the greatest and aged 25 he was behind only McEnroe (who didn't win another), and the above 4. He hasn't won one as a 26 year old yet so he's got a long way to go to catch up those in double figures.
4) Murray's slow start to winning Slams, mirroring his coach Lendl, is demonstrated as well, with the two of them being the oldest to claim their maiden slams from this list.
5) Agassi won more than half of his Slams after he turned 28, so there could yet be lots to come from RN/ND/AM all moving into the 2nd half of their careers.
6) I'm really geeky
PS I sort of just chose players who are best known for the chart, and left off the likes of Laver/Rosewall who won Slams both pre and post-Open era because it was too confusing.