Info on lounge access in the new program is out. At 50 nights, access to the lounge kicks in. For properties with lounges, here are the details, including what is offered when the lounge is closed.
Follow this link to the actual document https://members.marriott.com/wp-content/uploads/2018/05/MAKHAR18008_TBOP_Microsite_Platinum-Elite_Lounge-Access_Final.pd…
For the most part, this looks pretty similar to the benefits currently related to lounge access.
Pair this info with the post on Platinum Elite Welcome Gift (new program) and we're getting a much better picture of what the new program will look like.