Because everyone knows that Sweden is the most important country in the world. At least that is what our government seems to believe...
This election will actually be interesting. SD will probably get 25-30% of the seats and become either the largest or the second largest party. Neither the right-wing alliance (M+C+L+KD) nor the red-green governing coalition (S+MP(+V)) will be able to form a majority government. Furthermore, the Greens, the Liberals and the Christian Democrats are either below the 4% threshold or very close to it according to the polls, meaning that possibly 3 out of 8 parties could drop out of parliament, and something like 10% of the votes could be wasted. At the same time, the Feminist Initiative is closing in on the threshold from the other direction. If they enter they will basically be the Greens 2.0; if they get 3.9% or so they will pull left-wing votes, benefiting the right-wing (and SD).
The most likely government alternatives are SD+M(+KD) and S+C+L(+MP)(+V) respectively. S is effectively a welfare party for immigrants these days, and L, C, MP and V are fanatically pro-immigration. None of them want to touch SD with a 10 feet pole. However, C has lately profiled itself as the neoliberal party - their recent rise in popularity is all because of their new leader Annie Lööf who fancies herself as some kind of swedish Margaret Thatcher. If they go into a coalition with S, let alone V, they will alienate their new core supporters (their traditional rural base is already moving over to SD). L do not want anything to do with V, and even MP is stretching it. On the other hand, L has a long history of being shifty as f**k, so you never know. In any case, the latter coalition would be very uneasy and alienate a lot of voters.
Another possibility is that the right-wing parties will enable a left-wing minority government, or vice versa, by abstaining from voting. This will result in a weak government much like the one we've had since 2014, and cause even more voters to abandon the old parties in favor of SD. Especially if M does not take the chance to bring down S by allying with SD, M will be annihilated.
Some people hope for a grand coalition between S and M, the traditional "arch-enemies" of Swedish politics, like has happened in some european countries to stop the nationalists. I can tell you that this is extremely unlikely, and if it somehow does happen SD will grow even bigger the next election, either from getting more votes or from more voters abstaining or voting for some joke party, because people would be absolutely furious. Especially considering that polls have consistently shown since the 90s that the majority prefer SD's immigration policies, a Grand Coalition that sacrifices traditional left-right issues in order to defend mass immigration would be political suicide in Sweden.
So at the end of the day, I think that SD+M will form a new government, possibly with active or passive support from KD (if they make it into the parliament). If SD overtakes M as the second largest party, as the polls suggest, the next Prime Minister will be Jimmie Åkesson, and M will be reduced to the status of a junior partner in a coalition. That would be very pleasing to see in and of itself.
And if this somehow doesn't happen in 2018, it will definitely happen in 2022.