I think both can do it if they can get the supply issues straight. In fact, if all of the systems became readily available tomorrow, I'd be shocked if they didn't both reach 14 million by the end of the year. There's a ton of pent up demand right now, and this holiday season should be huge, as the second holiday season for a new console typically is.

Of course, the longer they take to straighten out the supply issues, the less likely they are to hit the number this year.  We are 5 months into the year now, so time is really ticking away. 

And will barely reach 2 million in 2021 after 5 months.

I've said 6-7 million sales for 2021 last december, I'll keep my estimation.

I read on neogaf that PS5 production is something like ~1,1m pr month, and they basically sell them as fast as they make them currently.
When we got numbers last time (april), from March 31st (I think it was?), it was that it had reached over 8m units sold.

Add another 9 months of like ~1.1m, and PS5 could be around ~18m by years end? (at current production rate) (if they up it, it could go higher)

PS5 is surely makeing it past the Wii U this year.
The XSX/XSS is the real question (theres no doubt the PS5 will).

I think XSX/XSS end up falling short of it (by years end), but again, its mostly down to production.
I think Xbox team, misjudged demand for the XSS, and made more than needed of those, and fewer XSX's.
And their production rate, was conservative, due to how it got burnt last gen with XB1.
They wont be able to make enough units, to reach the Wii U by 2021 in otherwords.

That is basically my expectations. I don't see any significant production ramp up for either system, so Whatever their pace at this moment will roughly be kept until the end of the year with small improvement and sure they may be keeping some of the inventory not shipped to have big holiday.

PS5 will probably outsell the Vita too.
Xbox, well, at least it'll outsell Dreamcast and Saturn I suppose.