I think Keith could certainly fairly soon be both in top 100 for doubles if they played much more together.
However, their paths are liable to separate a fair amount re singles and I wouldn't like Anna to take her eye off the ball in working to continue to rise in the singles ranks.
Yes I agree with you, Anna should carry on improving in singles. The confidence from this should do her good, and I would love to see another late-ish bloomer in singles.