So with this major change, JL Group's HND/NRT breakdown of International Flights will be almost even starting Summer 2020:

NRT: Current: 31 Routes / 40 RT Flights to 27 Routes / 34 RT Flights
HND: Current: 15 Routes / 22 RT Flights to 24 Routes / 34 RT Flights

But from the press release / media interview, JAL is also planning to further increase anywhere between 3-5 routes/destinations to/from NRT within FY2020.
These additional routes/destinations are on top of what were already announced earlier (VVO, SFO, BLR, ORD, etc.)
A target to have at least 40 RTs (same as current) is set which means that if you count Zip Air's (ICN and BKK + 1 Inter-Asia New Route), JL mainline is expected to introduce at least 3 routes to reach the target 40 flights.

Also, it was announced that JL bought the Jetstar Japan shares of Mitsubishi Corp and is now the biggest shareholder at 50%. IT is expected that JL will further expand cooperation with GK for domestic connections in/out of NRT moving forward.