Yes, standard DVDs will be around for a long time still, simply because the Blu-Ray players will still play DVD. So you will be able to find bargin DVD's and watch on your Blu-Ray player. I would say though in about 3 or 4 years there wont be anymore DVD new releases movies coming out, just older movies and shows. Since blu-Ray is intended for use on a 1080p HDTV I would say that if you don't have HDTV it is not worth buying Blu-Ray. If you do have an HDTV what is the resolution? If it is 720p you still wont benefit from the best picture quality Blu-Ray offers.
But if you are ready to jump up to Blu-Ray then I would say get a PS3, its the best Blu-Ray player available even if you do not want to play games on it.