New kit will be needed, but there's the positive side that costly ground infrastructure won't be needed, so it will open up access to unequipped airports at very little cost. For larger airports it will provide a backup to ILS. In Europe, I think the EGNOS system (which augments the American GPS signal, making it accurate enough to navigate from) will be chargeable for aviation users though, so swings and roundabouts.
The biggest winners will be ANSPs, the european SESAR scheme hopes to reduce ATM costs by 50% with the introduction of new CNS/ATM techniques, but will this cost saving be reflected in their charges? Theres a thought that landing fees might be lower for satellite approaches because the user won't be using costly ground equipment (links to my previous point).
I guess over time unequipped aircraft will be become rarer. At the moment, some aircraft on transatlantic routes receive clearances via CPDLC, and automatically make position reports using ADS-C. But unequipped aircraft continue to communicate using voice.
Personally I think its great, as long as its backed up by adequate training