Between now and then, roughly 9 Tunguska class and 1 continent killer will hit
And most likely we will have 0, that is zero, warning of their impacts.
While 1950 DA was detected because it is so large, nearly all of the smaller ones have not been found.
These things hit chaotically, and one could hit in the next instant, tomorrow, or 200 years from now. But one thing is certain, and that is that they will hit.
If they want warning of the continent killer, that's going to cost about $170 million for the LSST, which was the number one astronomy priority of the NRC and NAS. Reliable detection of Tunguska class impactors is going to cost more.
EP