This will mean another $16 billion will spent until 2022. There has been about $30 billion spent on SLS and Orion up until the end of 2018. A test launch of obsolete hardware will be the purpose of the additional spending. The EM-1 mission will finally test the SLS and the Orion capsule together. It will also launch some cubesats. It will be the first test and it will cost at least another $12 billion to get to that test.
The follow-up EM-2 mission would occur sometime in 2023 or 2024. The EM-2 mission will possibly have the first crewed mission of NASA's Orion spacecraft. It will be a lunar free return mission.
Previous Deputy NASA administrator have called for the cancellation of the SLS. In 2014, Lori Garver called for the cancellation of the SLS.
The SpaceX crew Dragon should be certified to launch human crews in 2019. SpaceX should have regular launches of the Falcon Heavy starting in 2019. SpaceX will be launching the Falcon Heavy two to four times per year from 2020 onwards.