Actually, I have been planning to get ready for a Pentax FF system for years and every time I bought a new Pentax lens I had that in mind. Well, below is the case for my current lens setup:-
1. Currently, I have 10 original Pentax primes, amongst which only the DA21 is not FF compatible, so the complete FF range is ranged from 28 to 300mm. The old "film" primes of mine include A, FA, FA Limited and FA* lenses. In addition, my existing three DA primes (namely, 35, 40 and 70) are all FF compatible (see my own samples here and here). In short, there are 9 lenses (out of 10) that can be used on FF!
2. For zooms, I still have 7 Pentax AF zooms amongst which only two DA standard zooms are not FF compatible. Other lenses are F, FA and FAJ ones and the made-up zoom range is from 17mm (fisheye) or 18mm (rectilinear) to 200mm. So, no problem again and I do have 5 FF zooms (out of 7)! :-D
3. I also have two FF tele-convertors by Kenko which is in full KAF2 compliance, i.e., with power zoom (SDM/DC) contacts.
So, all in all, I already have 14 original Pentax lenses plus two fully compatible AF tele-convertors (and also two other Sigma lenses that I rarely used, i.e., 18 lenses in total) to begin with when just overnight a Pentax FF DSLR body appears! Note that most of my lenses are AF lenses and full functions and compatibility is ensured and the focal range has been well covered. That must be really great! :-)) As for new Pentax FF lenses that are to be launched, I am sure that I will not hesitate to invest further if I can see the future of Pentax later on (but not now)!
P.S. If this time the rumour turns out to be not true and still there will be NO Pentax FF by early 2013, I think I might sell most of my Pentax gear and concentrate to build further my Canon system and make it glows. The wait should be over, for more than ten years, shouldn't it and shouldn't I?
P.S.2. I have another 13 lenses for other systems. possibly soon to be 14, when the Canon new pancake arrives!
P.S.3. How about your case? Welcome to share in reply! :-)
Related:-
Compatibility of DA Lenses on Full Frame
Two Major Meanings of Full Frame - Choice of Shallower DoF and Most Optical Quality from (FF) Lenses
Old Question: Will there be a Pentax Full Frame DSLR?