It looks like they are serious about taking a chunk out of GoDaddy.
From what I can see it's a long term promotion to attract new domain registrations, and in my opinion it's a smart lost leader.
1. Renewals remain at regular price.
2. They will massively increase their user base.
3. Registrations loss will probably be offset by dropping and aftermarket sales.
4. Perfect opportunity to introduce new services.
5. Will be able to claim 2nd largest registrar with hopes of one day catching GoDaddy.
6. With Namecheap it will be cross platform.
I predict Spaceship will acquire or merge with other registrars to become the only real alternate to GoDaddy.