If you are willing to speculate on some advances that hermetic magic might make over time then there are some cool possibilities for how magi might operate going forward in a world where the dominion is even more dominant than in 1220.
For one thing holy magic might stop being seen as hedge wizardry and become more common. Someone with access to holy magic can operate without difficulty in even powerful dominion auras (so long as they don't want to sin, which is admittedly quite problematic for some magi).
Maybe someone will rediscover the ReVi guidelines for supressing auras (in LoH). In that scenario urban covenants aren't limited to those rare and often awkward Lacunae where magic auras persist despite the dominion, they just have to find somewhere that has a subsumed magic aura and use a ritual to temporarily suppress the dominion aura to reveal it. I imagine subsumed magic auras are much more common. Worst case scenario supressing the dominion aura with no subsumed aura at least means no penalty to casting and lab work.
This would pretty much just be a second ritual in addition to the Aegis of the Hearth. However, a problem with this is that to suppress a level 3 dominion aura (which is common in cities) for a year with boundary target as with an aegis is going to be in the order of a level 60 spell, and it has to be cast with the penalty of the dominion aura - so in practice it's more like casting a level ~70 spell. Casting at night when the aura is lower might help a bit.
If you limit viable locations to weak spots in the dominion maybe you can get away with a level 55 spell (~60 after aura penalties) or even a level 50, but that's the floor. Still, that's not so easy for one magus unless they are quite good at ReVi. So maybe in this future there are magi who specialise in this kind of magic and are hired by covenants to perform such rituals. Perhaps the neo-mercurians, with their bonuses to ritual magic, take on a more prominent role in the order for this reason.
On that note maybe the structure of covenants changes. Urban covenants end up having to be centred around one or more magi powerful enough to learn and cast spells to negate the dominion, and wizard's communion becomes as common as pilum of fire.
But that's all fairly tame, the really interesting innovation in this vein is someone integrating (fully integrating into hermetic theory, that is) either the complete research of Conciatta, or new research based on original work or the Learned Magician magic, allowing magi to use realm lore to be unimpeded by hostile auras.
If you accept the ideas in the Conciatta chapter of LoH then if the confluence of the realms is integrated any magus with a dominion lore of 3 can operate pretty much unimpeded in an urban environment. Dominion Lore of 6 is basically immunity to dominion lore penalties except in the holiest of places.
So perhaps in that possible future all magi learn a smattering of realm lores as part of their standard education and covenants can be pretty much anywhere with only a mild loss of power from not being in a magic aura.
That's all not really addressing the main topic here and is more about how magi might continue to operate in a highly urbanised society, but it does built to a really interesting radical idea that could have pretty big societal ramifications - those high level rituals mentioned earlier could be cast over entire cities. I wonder what would happen if magi started negating the dominion aura of entire settlements for multiple years? Would the dominion begin to fade? Would other auras be able to grow in power again? Or would the divine simply intervene and smite the hell out of anyone who tried for daring to replicate an interdict with magic?