Is there enough satellite data storage for every a/c to send back FDR/CVR data in live time?
Short answer, No Rat 5.
Accurate answer - satellites have virtually no storage compared to the data they relay. Storage typically occurs at ground stations or data banks networked to the downlink site. On a SATCOM equipped aircraft, the prime limitation is bandwidth which in satellite terms equals dramatically greater cost.
The space bird companies would surely build to accommodate any rea$onable demand.