I have lots of respect to the guy, but realistically the only scenario where he would become Russian president would be if the vote for the Russian presidency was conducted in the West. He would win a landslide victory. In Russia though, if you go outside Moscow and St.Petersburg, it's not that people are against him — they simply never heard of him.
In the USSR in the 80s there was a lot of talk of one Angela Davis. She was presented as "the only opposition leader" or something. There's no doubt that if the election for POTUS was conducted in the USSR, she'd win over Reagan by a huge margin. In the USA though not many people knew who she was. So Navalny is the Angela Davis in reverse — the media across the border makes him look like punching in the weight category he does not really belong to.
Regarding Russian political landscape, you can look in any corner, from Gorbachev to Solzhenytsin and anything in between. There are not many points that these people could all agree on. But not a single Russian politician was comfortable with the thought of Ukraine joining NATO. And this includes Navalny too.