I wouldn't bet on this:
- The lifecycle on the market for a smartphone has shrunk to 9 to 12 months for the last two years. The Xperia 10 was introduced by Sony in early spring 2019.
- A typical sign of devices being EOLed is that Amazon themselves stops selling them (i.e. only "Amazon marketplace" sellers remain): This is already the case for the Xperia 10 and 10 Plus.
- It already becomes hard to obtain the Xperia 10 Plus at the Amazon marketplace at all (new and for a reasonable price).
- The "final" price at Amazon (marketplace) for its predecessor (the XA2 series) was ~€200,- for the regular model and ~€300,- for the "Plus" model, before it stopped being widely available (in late summer 2019). This is where the Xperia 10 (<=€200) and 10 Plus (<=€300) are right now.
- I expect the recent release of SailfishX for the Xperia 10 to slightly speed up selling the last devices in stock (in Europe).

Hence you might be better off ordering one now.

P.S.
What frightens me a bit is the announcement of a "great announcement" in early 2020 WRT future devices and the future of SailfishOS.
The last announced announcement (originally in the monthly Maemo-IRC community meeting) was about the "future" of Linux (kernel) and AlienDalvik on the Xperia X, and the final revelation last week was quite a disappointment after weeks of keeping users anxiously waiting for it. And this was just an announcement, not a "great" one.

Could you tell little more specific please?

You got me worried... - So, is this the end of Sailfish-OS saga?

Bought 10 on Amazon just the other day. Both are currently discounted in UK and don't seem very hard to find. Maybe you're talking about the German Amazon - I think BF sales depleted the stock, as Xperia seems more popular there. Both 10 and 10 Plus are still available in the Sony e-store, which contrary to UK sells phones too in Germany. There even was a 10 and 10 Plus sale in it this Monday (CM).

https://www.amazon.co.uk/s?k=xperia+10
https://estore.sonymobile.com/de/son...-es-it-315314/

"I wouldn't bet on this:
- The lifecycle on the market for a smartphone has shrunk to 9 to 12 months for the last two years. "

I concur
I have been thinking on this fact the last few years
The fact that with device lifecycles becoming so tight
inevitably one of two things must finally occur
1- a radical and far reaching innovation that "normalizes" device lifecycles must occur
or
2- sales, marketing, companies, enduser device ownership of devices, the entire ecosystem reachs a point of "unsustainable peak futility", popping like a bubble.

and due to the entire realm of smartphone devices and the deliberately planned obsolescence for profit, along with the lack of risk taking in the industry easily observed as advancements are by micron , not by inch or foot or mile as an industry standard..

I believe the entire industry, and how humanity interacts socially is in for a colossal disruption...

woo hoo
circling the drain baby!

There is a worry, i.e. the lifecycle of mobile phones as mentioned already. If we include the time Jolla needs to finalise the porting, then the lifecycle is getting a lot shorter.

Spending 250-300 every year for a mobile + licence is getting expensive. An official port for Fairphone3 would make more sense, but I guess we like big and flashy devices.

I've just checked the local (Czech) price comparison site and there are still many local sites selling both Xperia 10 & Xperia 10 plus:

https://mobilni-telefony.heureka.cz/...4gb-dual-sim/#

https://mobilni-telefony.heureka.cz/...4gb-dual-sim/#

(Sorry for the surprise Czech lesson. ;-) )

Also, even if you can't get a new in warranty device from a shop, people will be selling second hand devices for years to come & at very low prices compared to a new device.

A while ago I got a second hand Xperia X for a family member and the price was about 30% of what I paid for a new Xperia X just a few months before. The only real issue is making sure the device is in good working order and has a bootloader that can be unlocked. You will completely blast away any remaining data on it during flashing anyway.