1) Valve and their Steam Machines.
2) PS Vita
3) Wii U

I think Gabe Newell really needs this kind of failure and he will get it in a VERY bad way.

By the time this Gen draws to a close, I imagine Gamestop will be the big loser

You must also be Canadian lol "everyone is a winner" should be our national motto. 

You're completely wrong.

1st party games cost money to develop and market.  When they sell they could make a loss, break even or make some profit depending on sales.  Never 100% profit when you subtract the costs.

3rd party is almost pure profit, and they make up ~90% of Sony's sales.

You think Nintendo is happy that SM3DW outsold Killzone, but Wii U sales are still languishing?  Woot, Nintendo made sales of $30~40 mil or something.  That ought to keep a company that costs $1.6 billion to operate going.  Not!

Getting the user base up to 10s of millions, and getting far more titles out than a few 1st party titles a year is needed.

the gaming press if it can't reform itself

This.  Plus, I think Sony is going to enjoy when the PS4 is actually being sold for decent profit and they are selling 10's of millions fo them.  And like you said, they have all that profit rolling in from 3rd party games on their system, which for the most part are outselling their One counterparts due to higher install base and having the superior versions of those game.  If things continue the way they are with sales, 3rd parties are also going to be more likely to develop exclusives for the PS4 (without incentives from Sony), as it will cut down on costs, allow them time to exploit the HW to its full potential, and get an extra hype push from being an exclusive.

@ OP

In terms of home consoles, it will probably be Nintendo.  They went from market leader to (soon to be) 3rd place this gen.  And that's with a full year headstart and seemingly little chance of recovery, like Sony was able to do with the PS3.  I don't think they are making much, if any, profit from the HW.  And SW sales are helping them much, either.  If they don't turn things around, soon, they will be lucky to sell ~30M.  Of course, like gens prior, they always have their handhelds to fall back on.

Of course, it could also be MS.  So far, we've seen pent up demand from 360 fans who decided to stick with MS, but it's obvious that demand is dropping.  If you want an Xbox One, you can easily find one in a retailer near you and/or online.  It will be interesting to see how much demand has dropped when we get Jan NPD next month.  MS has already had many investors telling them to drop the Xbox division, since overall, it hasn't made them any profit.  They may have made up for the 360's losses by now, but definitely not the OG Xbox's.  And there was at least one of their CEO candidates saying that if he is chosen, the Xbox division will be sold.  I can many more investors jumping onboard with that if the Xbox One doesn't remain neck and neck with the PS4, and their gaming division sees losses for the first few years.

In terms of handhelds, it would have to be Sony.  At first, it seemed like the Vita would be able to go toe to toe with the 3DS, since it was much more powerful and was launching at the same price.  Nintendo knew the price points would give the Vita a fighting chance, so they dropped their price by $80, to $169.  This turned out to be exactly what the 3DS needed and it started selling gangbusters.  Sure, it won't pull DS numbers, but it doesn't have to.  Unfortunately for Sony, because their console was more expensive, and they wanted to sell it for around break even (probably only a slight loss) they wouldn't/couldn't drop the price, so the 3DS ran away with the handheld side of the gen.  Still, I don't think Sony will be hurting too bad from it, as they aren't taking losses from the Vita.  And the PS4 will probably help boost its sales slightly, due to remote play.  I see it doing ~30M-40M.

I nominate OUYA

If MS will really close the SW market for Windows 9 on PC too, Windows for PC will be the big loser, while SteamOS, Android and consoles (including XBOne, as closed market has always been accepted on consoles, and MS ones won't be an exception) will be the winners. Even without MS suicide moves on PC, console market could end without real losers, at least on home console HW, while on portables PSV is running the risk of a serious shrink compared to PSP. Anyway, just like PS3 in 7th gen, Wii U is sending the first signals that it can revive, so if Sony will support PSV, neither it should be ruled out too quickly.
On the SW front things are different, some publishers and devs are suffering, there could be casualties amongst them. It happens each gen, anyway, but with an economic crisis that is late to end in too many countries, some companies selling non essential goods will inevitably suffer.

I hate being right all the time .

Nintendo's revision of around a $200 million loss this FY is I think a sign of what I was saying.  Even with the 3DS doing well, the Wii & DS revenues are dropping and Wii U is not able to fill that void.  This will result in the need for Nintendo to scale back their console development, possibly retarget those teams to other platforms like smart phones.  Although TBH they could probably port their in development Wii U titles to PS360 & PS4ONE and recoup their costs, as well as make a lot of fans happy who would otherwise not play their games.

Realistically, Sony and MS will also be going through some similar losses as the PS360 businesses shrink and PS4ONE take some time to ramp up, but at least they likely have a future to new revenues in the next few years.

Like I said in the other thread, it makes me wonder what kind of crappy prices Nintendo is paying for the Wii U HW.  3DS is being sold for a profit, I believe, and SW sales are doing pretty well on it.  So, it must be the Wii U that is blowing through that money, and then some.