The cheapest thing to do right this minute is rarely the cheapest to do in the long run. It's usually a waste of money. Disc players should last a long time. Admittedly, they don't always last, but they usually do. So, in a roundabout way, you ended updoing the right thing. Because it simply...
I would do option 3. I would not do option 2.
Yes, 4K players can output regular HD, and they can downscale 4K discs for your current TV.
Option 3 makes a lot of sense, because it allows you to start collecting 4K discs, instead of (arguably) wasting money on regular Blu-Rays.
As far as...