Given that the three game modes, shared galactic background simulation and the ability to select which mode to play in (with a single commander and assets) on a session-by-session basis has been part of the published game design for over two and a half years now, despite vigorous opposition to their inclusion in the game, the game has now been successfully launched and we are now six months in, expecting the third content update, I would expect that it is unlikely in the extreme that mode switching will be limited / removed or that the modes would be given separate background simulations - especially as in the XBox One announcement, DBOBE states that XBox players will share the same background simulation and contribute to the same CGs and Power Play and also that all three game modes will contribute to Power Play.
While it might be published as such it in no way means it was a good decision. There are plenty of reasons why it should be re-thought and addressed to ensure longevity of the game. Open play depends on player population. If you reward players to play in solo mode, the open population suffers as a result. Since risk in solo is far far less, players naturally will flock to solo to avoid the risk of money in open, thus hurting open, thus hurting future sales.
Games with an open mode depend on active support and balance of that open mode. Allowing accumulation of wealth in solo (risk free) and transferring it to open ultimately ruins the balance of open and breaks the whole game.