Funny you should mention ADS-B as I have been dealing with a European company a lot lately who are at the forefront of implementing an ADS-B network throughout Europe, and they are installing the same gear in our new systems. I saw the display of the traffic, just from their small little antenna (and I mean small it was a 10 inch long piece of fibreglass!) whacked on the roof of their low rise building and the coverage was amazing.
The problem we have here in the Middle East is that it will take a lot of effort to drag the Saudis kicking and screaming out of the dark ages, and until that happens, their restrictive requirements tie the hands of all the FIR's down the line.
As far as the risk of losing satellite coverage, considering the number of satellites up there right now, the chances of that are slim and getting slimmer all the time. There will obviously be teething problems and challenges along the way but when compared to the huge initial outlay and maintenance costs for radar heads, and the fact that theoretically ADS-B antennae can be placed on oil rigs at sea etc, the potential for radar like coverage in most parts of the world is possible in the near future. If you own shares in Radar head manufacturers I would sell quick.
