I ' m sure the many people who want it will do many things to get it to activate there are many possible avenues . But the question presumed that regardless of that , it doesn ' t activate . I think that outcome is unlikely , but it ' s always a possibility if it weren ' t it wouldn ' t say good things about Bitcoin ! What happens if it doesn ' t ? The world doesn ' t end . On the down side we lose out on a lot of important improvements segwit itself , segwit derived features , and features people don ' t attempt due to doubt of activation . On the upside it would be an advance in the immutability of Bitcoin ' s behavior . One of the regrettable truths about free speech is that it can be best measured by the freedoms enjoyed by the most reprehensible among us . Of course people who say things everyone agrees with are free to speak , but we don ' t know we have freedom until we hear some horrible bigot expressing deeply unpopular views . So perhaps the token goes the other way We don ' t really know that Bitcoin is immutable to bad changes until we see it not accepting good ones . I think it is wildly premature for that Segwit is a great improvement which is almost completely uncontroversial on its own merits and there are still many elements of Bitcoin ' s design that could really use improvement . But if it didn ' t happen , it would not be an unmitigated loss .