One way could be to implement some or all of this along with changes to Android's "spacebar drag" cursor movement mode. Currently it can only move left and right unlike Apple's touchpad approach. Maybe I'm missing something but it feels like you could implement a lot of the features through a keyboard touchpad while keeping regular editing clunky but familiar. By expanding on an otherwise very limited feature it might be welcomed by power users without depriving anyone of their existing workflow and muscle memory.

One problem that comes to mind is that people are used to selecting from beginning to end and triggering the interaction from the bottom of the screen gives very little area go down while keeping 1:1 movement of the cursor. It could be solved by having the cursor hit the "roof" until the users finger matches the translated position then switch to a scrolling mode at the edges.