If we discount misinformation for competitors, then he's asking these rhetorical questions to hint at what's coming. My take:
<li>Does a mirrorless camera really need interchangeable lenses?</li>
Their mirrorless contender will have a fixed zoom not interchangeable lenses. Faster in-camera processing of lens aberrations means it'll be easier to cram in that zoom lens and maintain picture quality.
Can we make a compact or DSLR that can beat the mirrorless cameras? (they believe they have it)
They're attacking from both sides - DSLR for the interchangeable lens fans, compact with a zoom for everyone else.
Higher sensitivity rather than high resolution (probably refers to quality over megapixels)
It'll have relatively low resolution sensor and will be larger than the Nikon.
Keeping the camera small, with a zoom of around 24-70 at around f2.8 will mean no APS-C sensor; the lens will be bigger than they want. If Nikon and Pentax's small-sensored offerings do not do well then we can at least expect a larger sensor than these. Taking the hint of relatively low MP, the sensor will be based on a DSLR sensor but will be 'cropped'. How much will it be cropped? To a size that lets the camera & lens fit into a large pocket.