Nobody here has been prepared to say that they expect RFC 2047 encoding to
be around in 20 years time.
I expect that in 20 years time there will still be a need to read old messages
that use both 2047 encoding and old charsets.
I expect that for several years after adoption of any new message format
there will still be a need to be compatible with existing MUAs, MTAs,
UUAs, UTAs, and gateways.
Yes, it's probably desirable to migrate to a new format which relies more
on utf-8 and less on ascii-compatible encoding schemes. But it's not
desirable to dismiss the compatibility issues with handwaving.