The majority contributor(s) (i.e. those that are making you sign the CLA) can relicence their contributions, and keep your tiny contributions MIT licenced. Hop

The majority contributor(s) (i.e. those that are making you sign the CLA) can relicence their contributions, and keep your tiny contributions MIT licenced. Hopefully they can't relicence retroactivelly, so the previous version of the software stays available, but any following versions can be entirely closed source (but they keep your MIT licence notice).