Vinography has a great post examining the impacts of genetic modification (GM) on the wine-making industry. It is an interresting and contentious issue. I think that GM wines are inevitable and that, in blind tastings, they will do as well as non-GM wines. This means that, ultimately, GM wines will achieve a higher value and (typically) lower cost to the consumer than non-GM wines.
Nevertheless, non-GM winemaking has survived as long as people have had grapes and feet. GM wines will probably be great for the business (even the local and small commercial vinyards). But I think that the "soul" of the wine and winemaking will be lost with this transition. Of course, the foot-pressed wine lovers probably had similar laments regarding the advent of winepress technology.
In 100 years, we - or our children - will probably be all drinking GM wine or toasting the "quaintness" of the historic non-GM vinyards ("How DID they survive?" we'll muse).