> Actually, 7 phones got a final update (to 7.8) that bought most of the 8 features to handsets that otherwise lacked the grunt to run 8.
What 7.8 added was a few extra colours and a couple more tile sizes. Nothing more.
WP7 was WinCE based and incapable of utilizing more than a single core. It lacked any real multi-tasking and 'tomb stoned' apps when another was run. It had very limited background tasks, more like MS-DOS TSRs.
WP8 required dual core as one was dedicated to the UI (which is why it seemed more responsive) so it could not run on any WP7 hardware.
Apparently, no existing WP phones (other than 950 and XL) will get Continuum. Some phones may get W10M, certainly not all.