First, remember that a congressional delegation will mostly consist of returning incumbents, and transforming a party requires change over a long time, if you don't get the sitting incumbents to move with you.
Are those sitting incumbents Sanders-partisans? A bunch will say they'd like single-payer, 'n such, but Obama would have liked single-payer. Willing to waste time and energy on something that has zero chance of passage? That's another matter, and whether or not any of the sitting incumbents have decided that they'd take up Sanders's agenda if they had a working majority? That's another question. It's also irrelevant, at least until 2021.
Next, these are candidates. We don't necessarily know what supposedly antiestablishment-movement candidates will do once in office. Marco Rubio was originally touted as a great hope of the Tea Party, when he ran in 2010. Then, he became an establishment guy, just by being open to serious immigration reform. What will these Sanders-backed candidates do if they win? We don't really know. Ask the Tea Party what they think of Rubio now!
All of this points to the general problem of trying to build narratives about trends from a few anecdotes. Right now, there are a few anecdotes. That's not a real trend. Yet. (?)
Finally, as a longtime Sanders detractor, let me remind everyone that it's nice to have people who actually think about policy. Ocasio-Cortez, for example, doesn't. She is disturbingly like Sanders in that sense. A universal jobs guarantee. O....Kay. How's that supposed to work? Has anyone thought through the details on that, or are all of these people "details-schmetails" people? You
Its leader is Donald Trump.