If cession of Patagonian lands as part of an Argentine debt restructuring is a concern, I would sleep soundly at night. This is so unlikely as to not even be worthy of consideration. First, the original bond indentures, which will govern any Argentine debt restructuring, did not collateralize the debt with sovereign Argentine territory. Second, institutional creditors restructure debt financially, they don't take land. Banks repossess houses and cars. Mafia loan sharks break kneecaps. Institutional creditors work through attorneys to negotiate financial restructurings. Third, I would imagine that cession of land in exchange for debt to international lenders probably violates some aspect of the Argentine constitution. I don't have that as a fact, but most sovereign nations have clauses like this in their operative governing laws. Fourth, such an exchange would likely be politically impossible.
There is only one modern situation (that I am aware of) in which this scenario occurs: the absolute scum of the earth Chinese communist government. For several years now, the communists in China have given below market bids for infrastructure projects to 3rd world countries. The projects must involve large percentage of Chinese labor and corporate resources. The loan terms are generous, but beyond the means of the borrower/nation. When the nation falls behind on the debt, the scum in China take the project and viola - they have a new strategic port or bridge or toll road, at the expense of the 3rd world country.
China is bidding on a dredging project in Argentina right now. Look out!