Because that's all they are - guesses.
The truth is no-one knows. The experts and analysts are not "explaining" anything. They are guessing.
If there was an expert out there who had confidently predicted Trump would run, gain the nomination, shake off countless scandals and win big, they would probably be worth listening to.
No-one seems to have done that.
The only real reference Trump made to the Baltic states during his campaign was a suggestion that he regarded NATO's Article 5 commitment to mutual defense as conditional.
As he has not retracted that statement, we must assume he meant it and that he still means it.
Nor has he retracted his numerous words of praise for Russian President Vladimir Putin, so we must assume he still thinks Putin is an admirable figure.
Lacking any coherent foreign policy plan worthy of the name and, moreover, having repeatedly stated that he regards unpredictability as a key strategic asset, we must also assume he intends to be unpredictable.
Therefore attempting to predict in what manner he will be unpredictable would seem to be a futile effort.
The US Embassy in Riga offered some words of reassurance. It could do nothing else. But it doesn't know what will happen now, either.
No-one knows. That is the simple truth.
The amount of analysis being published bears no relationship to the amount of truth it expresses or the likelihood of that analysis proving to be accurate in the short-, medium- or long term.
Your best guess, based upon your own interpretation of Trump's previous words and deeds, is probably as accurate as anyone else's.
We must wait and see what happens and, in the meantime, consider seriously those things that are within our own power.