Pek is now 30 and has 10 caps, although a number of those came on a tour where he was the emergency 3rd hooker; the starting hookers in Australia being, I think, Moore, TPN, Fainga'a and McIssac, but McIssac was off to Japan and Fainga'a injured before the tour, then Moore injured while on tour.
Tet is 27 and has 2 caps. Slipper, Sio, Ryan, Daley and Toby Smith all have more caps and are the same age or younger. I think Tet should get a few more caps, but probably it'll be the odd one here or there as injury cover and/or the extra man taken on a tour.
Pek and Tet are basically good enough to hold their own at Super Rugby, but aren't dominating props and probably won't improve significantly now (unless the new coach hires some of the Essendon medical team or asks Lance Armstrong for some contacts! ;)). It's not worth discarding either of them unless we have new, young monster props pushing them for their spots, and even then their experience would be handy off the bench. We just have to accept that the scrum isn't going to be an area of dominance for the Force with these two, but it shouldn't be pushed around, either.
For me, Van Wyk needs a bit more weight, but not gym weight. He doesn't need to look like Mr Universe, he needs to look like Alexander, Crockett or Franks with strong cores.
The coaches like Millar, but from what I've seen of him he's no improvement over the Pek or Tet (can't recall which side he plays!)
Hoskins and Heiburg have shown flashes, but are not consistent enough.
Heiburg's 31, so probably not worth retaining if we can sign Vui and/or Erasmus