I don't know what to expect, exactly. We're talking about a foot injury for a big man. Those things take time and really cut into cardio and lower body strength training. I can imagine they ease him in depending on his lower body strength and stamina.
You raise an interesting question with your use of the word "meaningful." The Patriots have a put a lot of time in with Newhouse this season. The results have been inconsistent, to put it mildly. It's hard for me, at a detailed level, to assess what Newhouse does well and doesn't do well in certain situations and against different types of opponents. Scar knows.
I start watching every play with the lines as a unit to see what's going on before worrying about what is going with the ball. I definitely notice when guys get beat or just dominated. One thing that is impossible to miss is that Newhouse has spent a lot of time blocking air.
I do know that platooning linemen works in many situations, and is common in short yardage and special teams. It will be interesting to see if they platoon Newhouse with Wynn or Cannon and under what circumstances. If Newhouse can carry some of the load as a swing tackle, that could be very helpful down the stretch.