Pelosi will not pursue impeachment because she knows it will hand control of the House right back to the R's. Swing voters will see this as highly partisan, impeachment talk will overshadow any positive thing that the dems will do legislatively, Senate will dismiss any impeachment resolution passed by the House anyway.
You could possibly get the obstruction to maybe stick for a article for impeachment if only you had evidence that the Trump campaign conspired with the Russians in with the election.