The box would have to decrypt HDCP, swizzle one codec into another, and re-encrypt. I spent about $50 on dongles and the better part of a weekend pursuing that angle to no avail. Sony didn't make the announcement ahead of time, so nobody had an FPGA module ready. Of course, a cynic would say that was the whole point.

I wasn't alone in having this problem -- the support forums were overflowing with outraged threads about this. Support would give non-answers, wait for someone to say something objectionable, and then use it as an excuse to lock and delete the thread. Rinse, repeat. They had it down to a science.

Active adapters of the sort you might need probably start around $70 and go up depending on the ports required. To get a 4k hdmi 2.0 to dp adapter would cost like $120+ for example.

I'm sure someone eventually made one to address the market need, and $120 sounds like a fair price given the complexity. It wasn't available when I needed it, and it doesn't change the fact that Sony just up and dropped support for old displays.