From Wikipedia:
> On 19 May 2017, the Swedish authorities dropped their investigation against Assange, claiming they could not expect the Ecuadorian Embassy to communicate reliably with Assange with respect to the case. Chief prosecutor Marianne Ny officially revoked his arrest warrant, but said the investigation could still be resumed if Assange visited Sweden before August 2020. "We are not making any pronouncement about guilt", she said.
https://en.wikipedia.org/wiki/Julian_Assange#Swedish_sexual_...
I don't know much about it, but I thought he was worried that the UK would extradite him to the US for whatever reason they can manufacture.
Also, I'm not so sure about some of those facts you listed about the case. I saw a TV show about it, and the Swedish rape laws sound very odd, if I remember correctly a woman can consent at the time, then subsequently (the next day) can revoke consent, and that's rape under their law.
The prosecutors have physical evidence of unprotected sex recovered from the rape kit.
They have testimony from a long term ex-boyfriend that they never had unprotected sex, and that he can't imagine her ever consenting to it.
They have testimony from another woman Assange slept with earlier that week who claims that, while she wasn't raped, Assange really pressed (forcefully) the issue of not using a condom.
Given the circumstances, it seems like a reasonably strong case. Deserving of a trial, at a minimum.