Open Question: How Much Longer Is My MP3 Player Gonna Last?

I have a Sansa Sandisk MP3 player... i call it an MP3 simply because it is not Apple Ipod brand. But i have had it for about 2 years now, it has scratches on the back from it being in bags, and the screen is a mess because i cant find the clear screen protectors for it. But my real question was how much longer will it last me? - cuz im looking into and 8gb ipod touch (i would buy it a case and keep the protector on it!) and i was curious if i should start saving my money for it now, or not.. Thank you so much!! ;)