The MICROSCOPE mission tested the Weak Equivalence Principle (WEP) with an unprecedented precision of order 10-15 , two orders of magnitude better than the previous best lab experiments. While the WEP, the cornerstone of General Relativity (GR), does not sway, the decade-long problems faced by fundamental physics stay still: how can we unify GR with the Standard Model, and how can we explain the acceleration of the cosmological expansion? As most beyond-GR models predict a violation of the WEP, albeit at an unknown level, it remains critical to even better test the WEP. In this paper, we review the MICROSCOPE mission, give its final constraint on the WEP, and build on its experimental limitations to show how we could improve them by a further two-order of magnitude in the precision of the test of the WEP.