Creating a whole new UI system for what is ultimately just storing text sounds like the sort of thing that'd take a faaair amount of time to me, honestly. Like... nothing is likely to trump the current macro system, I'll concede that. But, I like my valuable power bar real estate and never built macros for the hordes of bases I visit. I just store the base passes in a notepad++ file, alt+tab, snag what I need, and paste it in. You won't be able to do that when the slash command goes bye-bye, granted, but, clicking a base portal and hitting alt+tab copy alt+tab paste is a pretty easy solution that doesn't put the burden of developing a new system entirely on the developers. Not a good permanent solution, maybe, but, something that you'll be able to subsist on until something else is put in place.
Edit: Or perhaps just e-mail yourself using the ingame e-mail? But the way text input works in this game is sorta weird and doesn't like copy/paste from the game itself sometimes, I find the text file way more beneficial, typically.