hi guys, maybe we should not start comparing apple to orange as both the brand are different. To answer the TS's question.
Is 4/3 good? - I came from the N camp during the days of film and switched to oly for digital by chance. Having the E1 and recently bought the E500, I find that oly system is quite good value for $$ (price vs performance) if you are just starting out with nothing (ie old lens etc). I have had a used D70 for a while as I have some old lens and decided to sell it away. One of the main pull factor for me is the dust buster and the zuiko lenses (even the kit lens can kick some serious a** man)
Future of 4/3 - I think that will depend on mainly the consumers like us as frankly speaking, oly with zuiko has come up with a pretty impressive range of equipment that can cater to the amature to professional not to mention other manufacture of the 4/3 system.
Finally, may i advise you to maybe start with a used oly E500 (I got a kit at $600 from B & S recently and its less than a year old!!!) and experienced for yourself. If you are not happy, at least you will not suffer too much a lost if you sell it away.