There is a reason why Old!Loki doesn't seem to remember things that happened in this series despite their claim of being a time traveller. (Even if we give them the benefit of the doubt and not make the most logical assumption that they're just lying.) Chances are this series wouldn't have happened without them coming back and possessing Thor or at least not entirely as issue #12 confirmed.
Also if their claims of Loki becoming them being inevitable were true why would they be here in the first place? Let's guess from Loki's previous time travel escapades: They is making things as they should be to create their world... according to issue 12 again, they want their own creation happen a bit sooner.
It's very odd that Thor claims to have no memory of his time inverted when every single other character who was inverted does remember (including Captain America, in Al Ewing's other title). But consider that Thor is a) Thor was roaring drunk for most of the storyline; b) not in a good place since he lost Mjolnir - denial is only the topmost layer); and c) Thor probably really doesn't want to remember it.
There are now 2 Loki's, both caught in yet another big Red Skies Crossover event. That means that Timey-Wimey Ball is in effect, potentially allowing both Loki's to continue to exist, one as the 'evil' Loki everyone expects to come back to canon, and the other as the Anti-Hero Loki we're coming to like.
King Loki apparently convinced Hela to release the Midgard serpent and join the battle against Asgard by inferring that this might save them all. What could that mean? According to issue #15 (as far as Hela know) they try to sever their dimension from Midgard, and as technically Asgardia is part of it it needs to go too. They could try to make the Ragnarok cycle repeat again though.
Issue #12's profoundly disturbing cover not only echoes what happened at the end of Journey into Mystery, but is also reminiscent of depictions of Cronus eating his children. And Cronus tends to be associated/mixed up with Chronos the Anthropomorphic Personification of time. "Time Alone Shall Murder All The Flowers" ... Oh, I get it!
The foreshadowing entry about Old!Loki using a bazooka wouldn't also imply that they might not be the future but completely different one altogether, given the current's still existing aversion to some technology, like guns? (Not to mention the conspicuously missing love for information technology... if they're the future, where did their TV, phone and internet connection go?)
And the Andvari's death curse entry: The whole "forcing truth on all" looks more like a side-effect of not wanting to let his murderer get away with it. (They still did.) But could this mean that said murderer Old!Loki is exempt from the "forcing truth" part, because they pretty much know the crime it was meant reveal? Well, they claim it works on them.