The Massachusetts Taxpayers Foundation predicts the state will see a $4.4 billion drop in tax revenues in the fiscal year that begins July 1, a figure that could grow depending on how long people are out of work. Eileen McAnneny, the group's president, said while tax proposals are likely shelved for the time being, the state will eventually need to figure out a way to pay for repairs to its crumbling roads and public transit system. "Some of those proposals will take a back seat in the short term, but the need for investments in transportation hasn't gone away," she said.