That's what I thought as well, until I actually started migrating. I learned a few things:

* You probably don't have that many accounts associated with the email, actually. I have about 50 accounts that I care about enough to move, which took me a morning, but it's doable.

* For the same reason, you probably don't have that many (real human) contacts as well. But I could be very wrong. For me, I still occasionally use Gmail to communicate with a few people (like every two months), but that's infrequent enough that I don't care about how bad Gmail is.

* You probably want to review which services you don't regularly use any more, and if you don't have precious data stored with them (you probably shouldn't), consider closing the account instead of changing the email address, if that's an option for the provider.

* You can of course keep checking the original inbox or do forwarding. My experience is that, very quickly, I only need to occasionally check the old email. I still get a few useful emails here and there, but it's manageable. (Plus emails that remind me I should just delete the account)

You can do it.