Transmit digital signals over long distances using current (voltage to current converters)?
There are two problems here:

I2C is bidirectional. It relies on the ability of the target device to pull the data line low, as well as the host device doing so. While you might be able to replicate this with a current loop it's going to be more complicated.

Timing requirements. Current loops aren't magic, they still take time for the signal to propagate. For protocols using a clock line the &quot;skew&quot; between the host changing the clock and the relevant bit from the target returning may be a problem.