Good prediction, it's more than likely now

With the One set to sell about 6.5-7 million this year, it would need to experience practically no yoy growth in 2015 in order for this prediction to come true, and that seems extremely unlikely. The One had a terribly slow Q1 and Q2 this year, Kinect really dragged it into the mud and with better pricing and more great software next year; I just see it as impossible that we won't see decent yoy growth. It should manage at least 9 million sales next year imo, leaving lifetime totals at the 18-19 million mark, which is too high for the PS4 to match this year imo.

I'd rather wait till the end of the holiday season to comment on this one.. I think we should all learn not to underestimate PS4 by now though, but this is pretty bold.

I don't think we have enough data yet. Earliest November, latest January
It really depends on the health of this years Q4 sales, 50% more than the rest of the year, which should be easier for XB1 and harder for PS4.

However, XB1 needs more than Healthy sales to close the margin.

Since I'm guessing here, I would say no, only because I expect momentum for both platforms to increase in 2015, and this comparison it would only benefit the XB1 cause PS4 2015 is left out.
At the same time, PS4's 2015 momentum is likely to shift XB1 sales away, simply cause a larger userbase grows larger, see friends and word of mouth effect.

Some of these PS4 predictions are becoming ridiculous. Soon I expect to see a "PS4 will outsell PS2 and DS combined" thread.

no way jose. xbox one will be past 20 million by the end of next year

IO think you're being too optimistic for the XBO, and negative on the PS4. XBO will be down/flat in Europe and ROW next year, and you think that we'll have 5-6 million sells in the USA for XBO? (Which is about what you'll need to get 9 mill a year, whilst being optimistic about Europe + ROW) Despite the fact that the PS4 is winning (often substantially) in the USA, which just leads to hive mentallity, which will only worsen the situatuion for the XBO. And it's not even like price cuts are an option at this point, as they've left it far too late for it to be uncomfortable for Sony to drop the price the XBO needs to drop to have a good fight. It needs a $150 price drop after christmas when Bloodborne + The Order drop to not get devoured by the PS4 (Which will sell 20mill+ in 2015).

I agree with op, I see 8mill tops for XBO at the end of this year, and 15 mill tops by the end of 2015. PS4 will be 17.5mill most likely by the end of this year. (37.5 mill end of next year).

It could easily be very close. If you're right about the 16 million PS4's by the end of 2014, then yeah, hands down this is true, XBO will definitely not make that by end of 2015.

I think it really depends on how hard Sony pushes for the rest of this year. They're going in hard in Europe with the Driveclub, LittleBigPlanet 3, GTAV, and Far Cry 4 bundles. I won't be surprised if SCEE does a Singstar bundle, too. If SCEA, follows suit and not just depend on the Destiny bundle, then I can see the OP's prediction happening.

Why would the One be down or flat in Europe next year? It had a slow year with a high price for Q1 and Q2 and few software hits for Europe besides FIFA, it has shown improvement in the UK and there is nothing to suggest that it will show a (near) unprecedented drop in Europe next year, there simply is no data supporting such a view, it is practically unheard of for a console not to experience growth in any major territory in their second CY.

The One has about 1.6 million in the US alone in 2014 and still has all of Q4 ahead of it, the 360 has over 50% of its lifetime sales in this region and the One has an even bigger percentage and has shown some potential here. The 8th gen has just gotten started, it is not unlikely at all that the One will sell another 2-2.2 million in the US this year, with Black Friday being a huge occassion and some big software inbound. Doesn't take a whole lot of growth to get to 5 million, certainly not anything beyond completely normal for second CY for home consoles. You seem to suggest with your "hive mentality" statement that the One might even be down in NA for 2015, which is beyond ridiculous.

You think there won't be any growth globally for the One in 2015? It is also finally available everywhere, and even though that won't make up millions; it'll at the very least make up several hundred thousand.

8 million tops for One at the end of this year?! You actually think it will sell only about 170k per week on average for all of Q4?! That is only slightly above the Wii U in 2013's Q4 (which was about 1.9 million and the most atrocious second holiday of any home console in 20 years or so). And that is somehow more realistic than my take on it? Needless to say; I strongly disagree with that notion, BF week alone should be at least in the 500k range. 15 million for the One by 2015 implies practically no growth; that is unheard of in the industry, heck: even the Wii U has been up a great deal in its second CY (40-50% is likely when the year is over). And PS4 selling 20 million next year? 50%+ up yoy? How is that realistic? Japan refuses to buy home consoles overall so this would put a lot of strain on other markets to make up all that growth.

I honestly don't understand how you're thinking here; you may disagree with me if you wish but your alternative proposal is incredibly unrealistic and founded on several cirucumstances that fly straight in the face of all we know about console sales and the gaming market. You are more less or less proclaiming that the Xbox One is dead since it won't follow normal growth in 2015 and expecting the same growth for the PS4 in its second CY as the Wii, despite the massive casual drive it had, low price and severe supply constraints for the entire first CY on the market. There is not an iota of data supporting anything you're saying here, you're going to have to construct a really, really compelling argument for how it will all be possible.