Festool states on the German website that the TBX 4/8 will be available in April; both batteries support Airstream.
Availability for the SYS-MC 6/4 is listed as June. Its maximum charging current is 6.0 A, so it is not a fast charger (Airstream chargers provide 16 A).
Batteries do not require Airstream; it merely enables faster charging by reducing waiting time for cooling and supporting higher currents. Tabless batteries do have a wider temperature range both for operation and charging, but they also profit from active cooling. All Airstream batteries can be charged in regular Festool chargers, including TBX 4/8.