Will Federal Employees have to come in? Will there be Social Security checks? Will there be a solution at the last minute? In many ways, a shutdown will be more painful this time. For one thing many Federal agencies have already had their share of unpaid sequester days, so there are no reserve funds available to pay people. I for one have had three unpaid furlough days out of a possible 5 (the remaining two were canceled). That means Federal employees have had at least 3 unpaid days this year, and are looking at possibly several more. Approximately 880,000 Federal Employees are looking at layoffs, not to mention extra hundreds of thousands of Federal Contractors who will also go unpaid as well.
A shutdown furlough (also called an emergency furlough) occurs when there is a lapse in appropriations, and can occur at the beginning of a fiscal year, if no funds have been appropriated for that year, or upon expiration of a continuing resolution, if a new continuing resolution or appropriations law is not passed. In a shutdown furlough, an affected agency would have to shut down any activities funded by annual appropriations that are not excepted by law. Typically, an agency will have very little to no lead time to plan and implement a shutdown furlough.
BTW, the funds for the implementation of Obamacare (ACA) are permanent funds separate from the main budget.