If the ROK Foreign Minister is to believed it appears the US will be offering a peace treaty and humanitarian aid in return for denuclearization steps:
Foreign Minister Kang Kyung-wha referred to ending the Korean War, establishing a communication channel between North Korea and the U.S., and humanitarian aid as possible measures that Washington could offer Pyongyang for taking denuclearization steps.
Korea Times
“Various options are being discussed as corresponding measures,” Kang told reporters in a briefing at the foreign ministry, Wednesday.
However, on resuming operations at the Gaeseong Industrial Complex (GIC) or tours to Mount Geumgang, which had drawn attention as possible reciprocal measures, Kang said such these “were not at a stage of being reviewed.”
You can read more at the link, but as I have said before a Korean War peace treaty is something that North Korea has long sought as a way to end the presence of US troops in South Korea. If there is peace why is USFK needed?
President Moon has been saying all the right things that USFK will remain after any peace treaty is signed, to include claiming Kim Jong-un understands this as well. However, this is likely just rhetoric to prevent energizing South Korean conservatives against a peace treaty.
Remember Moon is a very skilled politician that needs to keep the Korean right at bay and public anxiety down. If he openly advocated for a USFK withdrawal, that would give the South Korean right an issue to strongly attack him with and cause much public anxiety after decades of security guarantees provided by US forces. That is why I think the Moon administration will publicly say they support USFK staying, but will then have surrogates do things to make life difficult for USFK.
Possibly the future of USFK after a peace treaty could look a lot like the current THAAD site in Seongju. President Moon will say all the right things that he supports USFK, just like he supposedly supports the THAAD site, but will set conditions to make it difficult for its continued existence and cause the US to withdraw troops on its own accord.