This is true, for now. Had to start somewhere though, right? The next steps will be to try to get a foothold in less friendly parts of the country. It's going to be a really hard grind, and will involve a lot of losing along the way. Movement building is hard. (A lot of the younger supporters admittedly fail to appreciate that, and don't grasp that you can't just storm a 200-year-old political party in only one or two cycles.)
Things are well ahead of schedule though. With the races in the past few cycles, ALL of them were expected to be defeats. We were expecting people like Rashida Tlaib and AOC to lose in 2018, very badly - those races were originally looked at as glorified "fact-finding" runs, to develop strategies. Even the most optimistic of people behind the "Inside/Outside" efforts were not expecting something like The Squad & Co. to materialize until maybe 2022 or 2024. It's only 2020, and people like Engel are going down. I'm not at all discouraged about the results so far.