I would suggest that the 0-1 type restrictions apply to every 5000 points or part thereof (so a 15k game you can have three deathstrikes, three supcoms, etc) or allowing multiple forces (so a 10k game consists of two seperate 5k armies working together, which has the same effect but with a few more restrictions, but allows 5k of titans and 10k of imperial guard, for instance)
the other concern is mostly objectives/victory conditions. they break down fairly quickly (They Shall Not Pass is bloody hard at 5k, at 15k you're likely to find it even moreso, while with more and more firepower on the table, BTS will become easier the more points you have) I suggest doubling everything at or around the 15k point (so 2 blitz, 4 objectives on each side, need both blitzes for the victory condition etc. probably want BTS to be "two most expensive" and probably allow 1 unbroken formation for TSNP) if you want to do a 10k game, tweak the numbers a bit, or play a special scenario
Table size would also need to be increased (wider, deeper you have game length concerns. That said, I'd suggest you allow an extra turn before the two turns where conditions start to be claimed for every 5k aswell)

Basically, the game starts to break down in some areas right away, but with a few changes to scenario and force selection, (or atleast a willingness to say "yeah we'll just ignore that, lets do this instead") you can play fairly comfortably as big as you have time and space for.