Just some pure unadulterated speculation on my part. If there was a design problem or part sourcing or procurement problem, the body would have been delayed well before this point in time. The new body should be in manufacturing now, which to me would point to some sort of calibration / quality control issue. Pentax has been making cameras for long enough, that any normal body would not have presented any issue.
That leads me to believe that some new type of new technology may be included, that they may be having issues with in terms of scaling up the manufacturing process and not seeing their desired production rates and yields or some sort of unexpected quality control problem (alignment or calibration?). I'll go out on a limb here and suggest the optical viewfinder may be a hybrid (that they have a patent on from a couple of years ago). Pure speculation here in that Pentax touted their new prism technology, but I'm thinking that they were going to potentially surprise us with a bit extra here on this "feature", while shaking up the camera market a bit.
If they were to include some sort of hybrid viewfinder, that would take a lot of the sting out of not being able to go mirrorless, maintaining the DSLR form factor and being able to include some of the new future capabilities that mirrorless folks are pushing. I think that they are trying to be able to offer the best of both worlds - an optical viewfinder with a digital overlay, at an affordable price - and the new top end crop body would be the logical place to introduce this technology (with full backwards compatibility).
Just my 2 cents worth