If the government does shut down on Dec 21, could this delay if not halt newly won government contracts with private contract holders?

Funds are obligated at time of award so they cannot be pulled for any reason other than a termination or reduction of scope. If it is incrementally funded, then there maybe some impacts since a funding mod couldn't be executed (unless using no year money). Very few contracts are funded like that so I don't think you have anything to worry about.

Upon further review I think I am in the clear as far as funding goes. The funds used to make this position available came from USSOCOM under the POTFF and awarded to Nobilis SRS in June this summer. That being said it is from previously budgeted funds and 'should' cover the 5 year term of this contract position. My concern now however is whether or not a shutdown would delay my mission visa approval time. It is routed through Germany, then Rome, then US Italian consulate where I then go to pick it up after making an appointment to go in and collect it. Being those are all outside the US Government I think I'll be in the clear.

I was in contracting for some time. When we were "shut down", invoices still got processed, work was still being administered, etc. The reason is MONEY. Contractors perform many services and projects. Most of those services are needed every day. So they work; and then they BILL. There's this thing called the Prompt Pay Act which means when the Government receives a valid certified invoice, we have 30 days to pay or start paying interest. In the contracting world, a big dinger is having to shell out interest. It's big because it's easy to spot so that's what inspectors do. So it boils down as to who are the "essential" personnel. Keeping contracts going is typically "essential". We will frequently see new awards or task orders delayed unless there's a J&A (Justification/Authorization), hence essential. Those have to do with continuity of service most often and others like "if we don't award now, we'll blow another construction season."

I don't know enough about your contract, funding, etc. but suspect an initial award delay is probable if it doesn't involve National Security. The Contracting Officer typically requests the winning bidder to extend the shelf life of the bid (say 30 days). That can keep folk hanging but that's what happens when politics (aka irrational stuff that has no bearing on the need) intervenes.