"You're arguing semantics at this point"

Well, whenever you have an argument about definitions it is an argument about semantics. So we are both arguing semantics. 

"Both are part of the videogame market"

I'm glad we can agree on this

"What do you think happens if the 3DS is priced the same as the PS4 at launch?"

I don't understand what this has to do with why "consoles" excludes handheld consoles. Home consoles and handheld consoles are different, yes. Console's without the qualifier just means any videogame console. Home consoles means home, handheld consoles means handheld, consoles (or videogame consoles specifically) means all of the above. 

Well, I'm American and we're all idiots. No one should listen to us, including myself.  

It depends on Xbox Series X's performance which I think will be better than Xbox One's performance so currently I'm inclined to think PS5 will sell less than PS4 but so much can happen in the next few years.

PS4 had 0 competition, was a force in first party exclusives, had it's moment in japan when Nintendo transitionned from 3DS to Switch.
PS5 will start stronger with covid boost and whatever, but lifetime it's kinda way too early. I will say no. I don't see Sony dominating as much as they did with the PS4. We can see it probably will continue the decline in Japan. In the US i think the Xbox series X/S can put up a better fight in mid/late gen when Bethesda and their other studios starts pumping up great first party titles.

Switch started pretty slow, it was constantly on droughts for the first year and took off slowly until it's 4th year. I think the PS5 will probably trend a little higher until Switch hi 2020 and then we will see what happens from that point. But PS5 will never have a 30 million year like Switch is having right now.

I wouldn't say Switch started slow because that would be the equivalent of saying the PS4 started slow:

Launch aligned PS4 and Switch were very close for the first three years. The only reason you see them trading place like that is because of the launch dates being different. 

So right out the gate, Switch did as well as PS4 and then in the its fourth year it went into overdrive (making its first few years look slow by comparison)

I agree with everything except the Switch starting slow and droughts in the first year. The first year was stacked (second year was not), and Switch has been keeping up with PS4 until this year when it finally surpassed it (when you compare dates, not totals). 

We’ll Switch looks like it will continue locking down Japan so I don’t expect PS5 numbers to be better there gen over gen. Otherwise PS5 has some stiff competition this time around. PS4 was against WiiU and Xbox One going through a identity crisis. It was a easy choice back then, not so much now.

No. PS5 will be lucky if it can catch up to the PS4.

No. I think it will only reach 80 -90 mil lifetime.

Maybe I should have been more specific.

I don't think its an apt comparison between Nintendo and Sony hardware. You can't compare sales of the DS and 3DS to sales of the PS2 and PS3 for a variety of reasons. Nintendo handhelds can't be grouped in with their home consoles when determining "sales dynamics" in contrast to Sony's home consoles, as the original post I replied to concluded.