Nonsense. Trump was told by Grassley last Summer, that he would not schedule a replacement confirmation hearing for Sessions until some time in 2018.
Trump has also been told by some in Congress that they would charge him with obstruction and impeach him if he were to replace Sessions.
I think Trump is patiently waiting for the Congressional investigations and the IG investigation to finish. Then he will replace Rosenstein and leave Sessions be in his state of recusal.
And McConnell and others would not let the senate go into full recess last year to prevent Trump from dismissing Sessions and making a recess appointment to replace him.