I don't think they have any problem keeping their stance in the issue, it's a very confortable one because it'll never happen, but I think it's more conductive to trying to 'solve' the issue than the government's position. Podemos supports a proper legally binding referendum but that can't probably never happen without ammending the Constitution, which needs such a majority in both houses that it'll only happen if the PP is on board.

According to the poll, their base in Catalonia is pretty much split on the issue with a lot of undecided. I'm under the impression that a lot of their pro-independece voters are not strong nationalists and just believe they can reach their social goals more easily in an independent Catalonia, or something along the lines. Their base in non-nationalist regions is ok with the referendum, though they probably think it's not a hill worth dying for. From that point of view, their stance makes sense. They don't need an strategy or an endgame for Catalonia. The goal is simply to keep their voter niche.