Well, we can dream, can we … just take care that it doesn’t turn out like The Homer 
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1 … Sounds nice, someone should do that.
2 … Could be done via USB OTG?
3 … Define multiple, space is limited in a smartphone. Perhaps software SIMs will come to the rescue in that regard, but it probably will be harder to transfer them to another device if needed.
4 … Did you consider it could be Kaspersky’s fault? Crashes are not entirely a function of specs . Apart from that, smartphone specs will always be better in the future, and then better specs will partly get eaten up by new OS features and more demanding Apps and more stuff running in the background. Following your logic nowadays there should be no such thing as a PC feeling slow and lagging when you compare current PC specs to those of maybe 10 years ago, but somehow that still is perfectly possible .
5 … Battery technology and charging is already pressed towards the edge currently (and beyond, see exploding devices). Given time, it will get better …
6 … You already can opt to use Sailfish OS or Ubuntu Touch on a Fairphone 2. So it is a matter of the device in question being open enough for different OSes and somebody taking on the task of porting them to the device. And if you want to have a portable computer, you can have that already, see next point.
7 … Keyboard and mouse already work via USB OTG. I don’t know about monitors, there are some which can be connected via USB, that should be a driver thing then. But if you want to have cables, that would mean more ports. I don’t see that happening much with smartphones, there are small factor computers which will do that for you (e.g. the a bit crappily built and supported but otherwise very charming Gole1).
8 … Sure, why not, connection via USB OTG, driver and burning software thing then.
9 … Doable, but I wonder about the price tag …
Let’s compromise and meet at half of the screen size, it’s better for replying and quoting 
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