There’s no rush to change the storage. When there is 100Gb left that’s about 6 month’s worth of updates, and plenty of time to save for a 2TB card (which will hopefully be less expensive at that point). 
I agree with @XR219. I would not be concerned about space constraints, yet. If you’re wanting to install other Xbox games, then you might start to feel a crunch for space, but it doesn’t sound like that is a concern for you.
Relax, install content and give it time before you worry about looking for storage expansion options.
OK thanks
I don’t think I should have a problem for now with updates eating up storage space - as I only have flight sim installed
It might however be an idea to hold off the optional world updates - just in case I get mandatory game updates in the future that are really big
Having lived through every SU that has come out for the Xbox version, I’d not focus too much on this. Most of the time the updates are replacing existing files, so the overall size of the sim doesn’t tend to grow too much. There’s only been a couple of SUs that have added significant amounts of new content – namely the Game of the Year Edition and the 40th Anniversary Edition.
That’s good news - in that if mandatory updates overwrite existing files - the storage space should not increase too much
I remember last year the mandatory updates were rolled out pretty much every 1 or 2 months or so - but you think this should only be twice a year from now on
What is being included in the mandatory updates - is it bug fixes, new features, fasting loading times possibly
Having said that there is a well known fault of a missing toolbar when you load a saved flight - that is constantly being overlooked