Trump can issue a plenary waiver to Obamacare on day 1.
First, it can be completely gutted by the order of the Secretary of Health and human services, who can direct who gets a waiver, without limitation.
Second, all but a handful of aspects of it can be repealed in a budget reconciliation.
The filibuster is a non-issue. We don't need sixty votes. That is nothing more than obstructionist sophistry.