She might have thought no one knew before today... but Sinema started telegraphing it two years ago

Reading between the lines isn't necessary. Today, Kyrsten Sinema bailed on her commitment to the voters who put her in office. SHE KNOWS there is no path for her re-election in which she'd have to face Democratic primary voters in Arizona. She rationalized her way to leaving her legitimate base without so much as a goodbye kiss. 

Now, to take the bypass route directly to the general election ballot in 2024, she'll need more signatures from voters, but she'll likely have plenty of campaign cash hoping to get them. 

Of ALL of the commentators talking about this decision by Sinema today, MSNBC's Alex Wagner NAILED it better, more directly, and more dead on Bull's eye, that anyone else. Sinema's been planning this day for at least two years.

For perspective on where we (mainly but not only Arizona Democratic voters) go from here, I recommend Michael Moore's podcast.