It's possible Ram may catch Silverado in sales at some point. However, if you add in sales of the Silverado's twin, the GMC Sierra, Ram has a long, long way to go to catch GM.
Ram is clearly shaking things up right now in the 1/2 ton segment with their 8-speed trannys, Ram Box, coil suspension, and class-leading MPG's with both their gas (Pentastar) and diesel (Ecodiesel) engines. GM is just playing it way too conservative. The Ecotec 5.3 and 6.2 are great engines with good MPG numbers. Unfortunately, in the current "ECO" marketing fray, the ECOtec pales next to the ECOdiesel and infamous ECOboost.