Minority governments are legally possible (if a majority of parliament can agree on voting it in, and it can then be dismantled if it looses that support) but not practically feasible in the current political climate, as it would hinge on the support of either SD or the largest party across the isle (S or M). SD is populist to the bone and has outright said that they will break a government if they don't to influence things (in particular, immigracy politics). I still think the right-wing coalition ruling with the support of SD is the way this will turn out, but I certainly understand why anyone would be leery of basing their rule on the support of a party that has the stance of "lol we're totally going to stab this government in the back you if it suits us lol".
As for M joining the left side (S+MP+M, without the Left Party), well, when the current government formed a minority government in 2014, the right-wing collaboration, "the Alliance" (their choice of name) agreed that they would concede and not threaten the gov in order to keep SD frmbeing the weighmaster (they called the agreement called the "December Agreement"). They then regretted that dearly and the internal disagreement over this issue and the feeling of not being able to criticise the government nearly broke "the Alliance" apart, leaving them not forming a combined coalition platform in this election, but instead running as four separate-but-with-related-interests-parties again. Since "the Alliance" has been widely credited for being able to break the iron grip the Social Democrats have had on the rule for like 50-80 years or so, the breakdown of it was harshly criticised and was announced being the reason why the right would lose this election even before the election season began, especially from the inside of the Moderates (as they are the power party of the Alliance and basically decided everything, so the failure of the Alliance felt basically like them losing power). So we're at the point where any assent to the lefties will be seen in very bad light on the right, even if it is more of a compromise than the concession the December Agreement was. As such it is unlikely they will support a left-wing government.
As for S, I don't think them supporting a right-wing minority government is as unfeasible - but it would likely have the same effects on their voter support as if they outright joined a right-wing government. Ie, SD walks away with a whole chunk of their voters.