The Enterprise website is paywalled, and I'd violate copyright law if I posted the entire text, so here's a summary.
MDOT is going to close the Old Great Mills Road to northbound Rt 5 access by the end of August. There's design work to do, then the work to install signs and a new curb preventing right turns will be completed as fast as possible. It will involve deactivating the right-turn traffic signal at that intersection. The main signal will not be affected.
The Commissioners listed this intersection as their primary transportation initiative in their MD State budget request this year; Maryland moved the project forward as the only request for federal transportation funds.
There's also some discussion of long-term plans, including: "That money would widen Route 5 to an undivided four-lane section of roadway, and would add 11-foot-wide outside travel lanes, with 5-foot bicycle lanes along both sides of Route 5." It will also replace the bridge over St. Mary’s River.
Aside from what the article says, yes, residents in those apartments will have to exit Old Great Mills Road onto Great Mills Road, and go through the stoplight to go north on Rt 5. Not a huge change for them.