[Impossible]

Eye strain will be mitigated with eye tracking and varifocal displays (https://www.roadtovr.com/oculus-research-demonstrate-groundb...), as well as higher resolution. It might still be a problem because you're still staring a screen on your face.

Locomotion is less of a problem than people who think its a problem is, and I think that stems from a lot of people in VR being hardcore gamers, and exploration of large spaces being a core mechanic and selling point for 3D video games for the last 25 years. I don't think omni-directional treadmills or vestibular stimulation or anything inconvenient like that will catch on for locomotion, and I think we'll either use various forms of teleport, or sliding (traditional 3D) locomotion for the foreseeable future, and people will mostly be ok with it. It's possible that with wireless and/or standalone headsets that redirected walking, will be a popular option. You could imagine a headset where Chaperone\Guardian builds on SLAM used for inside out tracking, and can give apps information about the layout of your house, allowing for large procedurally created virtual spaces. This still doesn't solve the problem for people that don't have medium sized private spaces to play in, and also makes it harder to do multiplayer games where players are playing in very different spaces.