DD & DTS

Okay, I've read some reviews on the difference between DD & DTS. I understand some of it now. I'm not building a home theater, I just want 5.1 in my living room. I found a nice system for a nice price; hard to beat deal. It has all the usual features (DD, Proligic, DSP, etc.), but no DTS, or even Prologic II. My question is: is it foreseeable that DTS is going to pass up DD and I won't be able to rent DVD's with DD in 2,3, 4+ years. I know nobody has a crystal ball, but I'm not that up on tech. changes in the home audio world. I know I'll be happy with DD 5.1 unless it leaves me behind and new releases are DTS. Any thoughts? Thanks.