The Connect has been around a few years, and depending on SPDIF and thus the internal clock of the Connect is not a high-end option anymore. I'd like to see an USB-A digital output on the Connect. With this, external higher-precision clocks can be used (on the DAC, on other USB to SPDIF/I2S interfaces etc).
I wouldn't mind if Connect also would support high-resolution services from e.g. Tidal, but that would just be icing on the cake. I love Sonos Connect as the most versatile streamer in terms of easy to use and supporting many streaming services, but the lack of an USB interface puts me off. Add it, and I'd buy it in a heartbeat.
I know that there are companies modding the Connect, and that there are plenty of SPDIF decrapifiers, but those are just half-baked solutions.