If I take the high-profile “rape” trials I know about as a guide (mere allegations, scant or no evidence, a hungry press and tons of lawyers) this could take a long, long while with much opportunity for Assange to say whatever he wants and a lot of pressure for all involved parties. It’s not as though Sweden can lock him up and throw away the keys. He is relatively safe in British or Swedish custody, if anything were to happen to him the respective governments would get massive problems and there would be no plausible deniability.