Two of their 3 mounts are SLR mounts
And I agree regarding direction loss, but that happened decades ago; IMO they started regaining it right before Hoya took over (but too late to prevent it) - with the K10D and a nice set of APS-C lenses. 645D was also in development.
The first takeover was the effect of not being able to persuade their shareholders (between which Sparx wanted to sell no matter what) that they could continue on their own. Unfortunately under Hoya the execution started to suffer instead of improving.
The second takeover was the effect of the first: Hoya didn't cared much about the Imaging Systems division.
There's no silver bullet such as having a FF MILC for few months before the competition.
Pentax is already competing with Canon and Nikon, so it would be nothing new for them. All they need is to have an user base large enough to support the more expensive FF cameras (and lenses, those would be shared with APS-C users though).
They can do it because they're doing it, not because it's easy.