My gut feeling is that he did anticipate it to some degree (see his prior tweets), but the sheer scale of the vote-dumping + Fox betrayal in the swing-states caught him off guard, which is why he wasn't able to smack it down immediately.
I don't think the current situation was 'part of the plan'- the ideal situation is to be able to smack down cheating as it shows up and win a election normally. The current Plan B, of going to the courts and litigating is far more risky and has more points of failure involved, which is why I don't think it's the desired outcome.
Not sure why he wouldn't have considered the possibility of the Dems going nuclear, but then again, Trump hasn't been able to deal with social media censorship either during his term. Regardless, it's water under the bridge- there's only the road ahead at this point.
My main concern now is if we end up with another Boston Marathon incident involving the Biden crowds, or the courts are compromised as well...