I look at what Nintendo has done with the Switch, and it seems to be working out very well for them. It turns out, a console that doubles as a handheld is a more attractive option for people over a handheld with console-like power. Should Sony follow suit with a future iteration of the PS4? Sure, they could buy a Vita for remote play for the current version, but would it be better to have a device that's a PS4 at heart? Not to compete with Nintendo or anything, but for the convenience of people that prefer gaming in such a manner. 

Granted, such a repurposing would come with sacrifices. Likely a smaller hdd option and physical games would change formats, splitting the base, And it would surely come with its own version of a dock if they can't shrink the innards to a proper tablet size. Would it be a good idea in the end?

Yes, I would buy

the Switch's power falls somewhere between a Wii U and a PS4, so for Sony to make a PS4 portable they would need to either dial back on performance power which would only tick off devs and make them not support it, or they would need to make it expensive as hell which would tick off consumers and make them not buy it. also remember the Vita, which basically was a portable PS4 that people hated so much that Sony stopped making portable consoles entirely.

man... with all that in mind the Switch really seems a lot more planned out.

Could they?

Today; It would be very expensive for chip that powerful to be developed and created to work in the Switch's form factor.

Battery life would be lucky to last an hour on certain games, you can only squeeze so big a battery in such a small space.

And If it's meant to be grouped in with the PS4 eco-system disks wouldn't work which would be a problem for people who buy PS4 games physically.

It's probably not one of those things they should attempt right away. Just when the cost of the components are lower. Maybe at least a year or more. For all we know, they could be R&Ding something like that now. Giving people sticker shock over something like that would be fatal.

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If it could play all PS4 games with little loss in performance like the switch, then yeah I'd buy it. It wouldn't sell well with such a high price point though. If it's like the Vita, then hell no. Wouldn't buy and wouldn't sell.

That's a looooot of a stretch. Vita isn't as powerful as a PS3, how can it be a "portable PS4"? What he meant was a portable version of PS4 that played all your PS4 games. That alone would give it a game library miles ahead of the Vita (and, currently, parsecs ahead of Switch). The only games the Vita shares with PS4 are some remasters and indies. Remasters aren't system selles and people don't care for indies (if you don't believe, just read the comment section of the monthly PS Plus free games at PS Blog).

Anyway, it could only be possible in 2 or 3 years, due to power/heat constraints. It would also be a problem for people who have a lot of physical media, since it would be digital only (PSP Go failed hard at this, but digital is stronger now). Unless they figured out a way to authorize people to access digital copies of their physical media, I think that would be a no-go. The fact that it would arrive when PS4 would be at the end of its life it's also a big problem.

However, it wouldn't need 3rd party support since it would already have a massive library of games. It coule be a killer concept if done right, a bunch of regular PS4 owners would get one to play games on-the-go. I think it would be more effective if we ended up forgetting gens and just using iterative console upgrades, but that won't happen anytime soon. 

That could be awkward for Sony in that their new cutting edge PS4 games would likely not run well (if at all) on it (we're already seeing games run much better on the PS4 pro than the standard PS4). It kind of requires that it be your strongest hardware at the time so that the AAA first party games are made with it in mind.

In that sense it seems to me the PS4 and PS4 portable would be competing for the same market, and largely be a waste of money.

Still, they'd probably have to have begun development a while ago as pulling something off like the Switch reportedly took years of trial and error to make the form factor work. If they were to just start right now I imagine it'd only be coming out when their next console was about to show up.