Seriously, I think there's going to be a 3DS revision this end of the year. Here's the reasons
1) Japan has been two years without a new 3DS model. 3DS XL came out on July 28th, 2012. Two years indeed. This would be usually the right time for a new revision, in order to proprel hardware sales again, especially when...
2)...they're going down. Now, as already said, shipments are still infuenced by the big Holidays overshipping, so much that 3DS sold 200,000+ more in Americas and Japan than what was shipped in those two territories, so you have to count that as well, but sales are still going down. Especially...in Japan, best 3DS territory so far. Which is very similar (not number wise, but % wise) to what happened to DS Lite sales in 2008 compared to 2007. That year, DSi happened.
3) Shipments forecasts being defined as "conservative". Now, let's try to comprehend what could that mean. FY2013 ended with 12,230,000 3DS and 2,900,000 Wii U shipped. This year's forecasts are respectively 12,000,000 and 3,600,000. They seem to basically be based on what happened in FY2013 with some adjustments due to releases, age of the platform and other things. Wii U forecats is extremely low, but higher than 2013, due to having MK8 and Smash Bros., as well as other titles, coming out this year, compared to Super Mario 3D World and Wii Party U. Stronger lineup, thus stronger sales, even if not by that much to call it a turnaround.That's...something that should be reached by Wii U, and it could do higher than that too.
3DS, instead, is slightly lower than last year: end-of-the-year lineup should be not that far from last year (Pokémon remake doesn't have the same power Pokémon main has, but Smash Bros. should be better than Zelda, even in the West), platform aging being considered as well...but, last year, 3DS reached 12 millions also thanks to 2DS's launch. And Iwata himself said that those forecasts have been made conservative because "they're sure they will reach them". Now, of course, we have the evaluation component: last years, they sucked hard at doing forecasts. But this time, they seem to be at least trying to be reasonable: you can't tell me that they've overshoot with Wii U forecast, since it's higher than last year, but still poor at best...and since they applied the same reasoning to 3DS forecasts (conservative, based on last year happenings and what happens this year) , I suppose they won't leave it without a revision this year, at least in order to be as near to their forecast as possible.