Earlier quoted context omitted.
Former attorney turned software developer here! Nope, it's not a settled question in the way that I think you mean. Each ToS is different so each would be subject to individual legal analysis in court on its own terms. Questions would include whether the ToS is unconscionable, whether the terms violate laws of the locality/nation, and so forth. It's the same with traditional contracts - the fact that contracts have b…
So even the general question of "Whether terms of service constitute an enforceable contract" depends on each individual ToS?
So, under the current state of the law whether or not a contract is enforceable depends entirely on what the terms in that specific contract are.
Unfortunately, this is yet another instance where the law has failed to keep up with technology. Contract laws (at least in the USA) date back long before anyone ever dreamed up the idea of a EULA or ToS. Our laws contemplate two or more parties with roughly equal bargaining power sitting down and hashing things out, and go from there.
Laws based on that assumption are a pretty poor fit for a world filled with EULAs and ToS but it's what we are stuck with at the moment.