"- has a new type of mount and that Canon will provide an adapter for EF lenses (that was already considered to be most probable, nothing really new here)
- features an APS-C sized sensor and not the sensor of the PowerShot G1 X (most of us thought it would have this sensor)
– This is a new rumoured spec of Canon’s mirrorless camera, and – I guess – a very welcome one (if true)"
If this source is trustable: http://www.canonwatch.com/rumor-canon-mirrorless-system-camera-quick-update/...
I think that the direction in which Canon moves in respect of sensor size will be determined by economics: There is a trade off between the smaller area of the 1.5" sensor against the already huge volumes of APS-C EOS DSLRs that Canon produces. Which ever yields the cheaper design will probably be the route that Canon takes.
Depending how committed Canon is to the G1X, they still have to produce the 1.5" format sensor going forward anyhow.
Going for APS-C has the advantage of the fact that Canon usually has at least 2 APS-C sensors in production - providing sensors for models with different market positioning.
A different approach to just using 1 sensor format would be to use an APS-C sensor for the higher end models, and a smaller sensor (such as that used by the Nikon 1 system) for lower end models, while retaining the same lens mount - the same way there are APS-C, APS-H (that mention is for wickidwombat) and full frame EOS DSLRs.
