Why would they need to? They have a huge market that they are dividing up. I can see Microsoft making something similar from the PC side of things... I'm not sure that Sony and Microsoft even need to go after the Switch's potential market.

I could see Sony going that route if their console sales were really struggling, but the PS4 is doing quite well. Maybe they will release a new portable for Japan. 

If MS and Sony's hand will, somehow, be forced, it won't be now, but probably years from now.

Switch philosophy is that you can play everything, truly, everywhere. Just like mobile devices (with or without TV connection). MS and Sony's stance is less valuable: play at home.
This the image that these "players" send to costumers.

Thing is, we are living in world that is everyday, more and more about portability.
You start at one point but you are not hindered by it. What you create/do, you can take it with you.

Nintendo is not only more in line with this than Sony and MS, they are also making strides in the mobile department. Just look at Pokémon GO and what it did for 3DS sales and is doing to the new Pokémon games.
Nintendo is making a bridge and is creating the idea that gaming on it's consoles is all about mobility, portability.

This is where Nintendo can win BIG.
By using their IPs in both markets (creating different experiences is a necessary step) they are taking themselves out of one market and glueing themselves to what is, without a doubt, the future of gaming, the portable market; they are positioning themselves for the future. Sony and MS aren't.

It won't take many years before tablets are close enough to console gaming.
Nintendo handled this already and created a console that might (not confirmed, i think) work it's best at home (docked) but can also deliver great graphics and experiences on the go.

If they succeed, you bet that Sony and MS will try to follow them... again.

Don´t count Sony out just yet. If they get 4 or 5 well reviewed VR games they can still turn the PSVR into a cash cow for 2017.

Why counter it if U already doing good?

I deleted a lot of your post just for text's sake, it's right above this post anyways. I've always been a Nintendo fan, and most probably always will be - Mario/Zelda/Metroid/etc fit my preferences/lifestyle, a good balance between accessibility and depth, leaning mroe towards accessibility. I wouldn't say I'm biased just as much as an MS or PS guy or gal isn't biased, it's just what we like. I mention this just because I think you gave an extremely well thought out response that was very understandable.

Status quo isn't blah/meh/normal, it simply mean appealing to what the current trends want. Motion is cutting edge, and so Sony adopted it, just not as thoroughly as Nintendo did so that they still had room for the other elements of gaming that were popular at the time(3D genres, etc.), and thus had room for developers who could have an audience as well. And I think your sales argument matches this.

In a way it actually makes me feel like Microsoft is the one who really has to struggle as they seem to have an identical competitor. Nintendo probably harbors a greater risk/reward ratio; unique approach, no competition to eat up sales, but possibly no audience to eat up sales. As a fan I'm optimistic they've found a more realistic approach a la pokemon go/mario run and then somehow Switch factors in there.

Do they need to?

They can just continue with the PS4 Pro and XOne Scorpio since that is doing good already

Your not taking into account this is the current user base regardless of when a particular piece of hardware was first purchased, these systems are current or the latest iteration of their respective hardware lines  

We are talking userbase here, someone was saying Nintendo wasnt a market leader in this regard, which is obviously not true going by the numbers