There is a fairly hard physical limit to cameras - the quantum efficiency can't be more than 1.0, so you will still need glass (mirrors / lenses) to collect light, and the fainter the object, the more glass you will need. Current DSLRs are around 5 -10% QE (but getting better all the time) and the specialised astro cams approach 70%. The return on investment of going from 70% to 90%+ is not going to be eye-popping.
Noise figures are dropping all the time; the read noise of the KAF8300 is around 8e- and the dark current is proportional to sensor temperature. Christian Buil has an excellent website with camera QE and noise figures listed.
http://www.astrosurf.com/buil/isis/noise/result.htm
The mount and the glass will still figure prominently in the years to come. What will improve is the cost of good silicon to get images.
Regards,
Tony Barry