Orsinium has been sacked three time to date by armies of both High Rock and Hammerfell. Not necessarily in the immediate future, but do you think in time it will happen again? They are after all still inhabitating in what Redguards may very well consider to be lands belonging to Hammerfell. Do you think the Orcs may be able to stay strong in their new home and be accepted there for evermore or do you think they may have to consider relocating even further east to get away from their enemies?

There are certain constants in the Elder Scrolls Universe.

There will always be Necromancers

The Daedra will always mess with Mortals

And Orsinium will always burn

Orsimer are the children of Malacath. Malacath is the god of outcasts. That the orcs should have a permanent home is therefore contradictory to their very nature. Alas, Orsinium must surely fall.