The new forum will not cause people to disappear from Less Wrong, I expect. In fact, note the narrow focus of the IAFF:

Examples of subjects that are off-topic (and which moderators might close down) include recent advances in artificial intelligence and machine learning, existential risks, effective altruism, human rationality, general mathematical logic, general philosophy of mind, and anything that cannot (yet) be usefully formalized or modeled mathematically.

Less Wrong continues to be a great place to discuss those topics (which includes the topics you're interested in). And as for the technical topics, I hope to make some posts on here for the more digestible forum work.