Hello,
At present, we are only planning one more print book covering the Star League era: Historical Liberation of Terra, Volume II. A series of Field Reports covering the non-SLDF forces as of 2765 are also in the planning, but awaiting solidified stats so the authors will not be permitted to power creep their factions one after the other. This even includes nailing down all remaining ships and ship classes of the era, so that there will be nothing of substance left to explore. Combined with the last of the XTR: Primitives series, we will be done with the Star League and prior eras completely.
Hopefully that helps.
Thank you,
- Herbert Beas
BattleTech
Catalyst Game Labs