It would be reasonable for OMAG's board (aka, BoD) to extend the expiration of those rights if the timing gets tight. Right now, being early March, I wouldn't expect to hear anything on that. But if the DA isn't signed by later this month, I would expect that the BoD would decide to extend it. It would only make sense as, clearly, the BoD expected the DA to be signed, a great deal of interest in the stock to be therefore generated, and the rights to become extremely valuable to existing shareholders.
They put out the Rights offering for a reason and it wouldn't make sense to just let it expire. So I, for one, am just going to sit tight and wait. As for the warrants, there aren't any issues with those expiring.
Hope this helps!