Well, I haven't waited long. Perhaps, the guild repoens in the end Here is my experience:
The messenger appears in Harmondale about 14 days after the second phase of the game has started. If you ignore him then you get the invasion. Now, after killing all orcs and soldiers, I checked the guild and got the boss, who informed me about a "lesson" and about my bank account being pinched. I repeated my visit in the guild several times and I always got the same. Then I stopped checking the guild.

If the guild reopens in the end then it's desirable to know when. Has anybody tried when the guild reopens? Naturally, only the case when you refuse to rob your firends is interesting.