Wait for E7 or just get a Nikon D5200 or Pentax K5 II or K30

Hi

I have been using Olympus E510 with lens of 18-180,50mm,70-300mm lens for some time but thinking of adding second DSLR with HD video capability. I am not sure if both Nikon or Pentax can work fine with Olympus lens.

Is there any folks can give me your advise.

Thanks and Have a Great day.