Umm I think this is a little confusing at the moment. AND a little incestuous. Come to think of it.
1) Amara seems to be this really innocent , docile woman madly in love with the convoluted Silas ( no seriously, I do pity Qetsiyah. Silas was a jerk) . So the only way, both the Petrova AND silas bloodline would've continued is IF and only if Silas and Amara had a child. Which makes all of these epic romantics distant cousins, yikes ! Okay, forget that.
Confusion 2) Does this mean that our intial theory of petrova dopplegangers being born every 500 years is false ? If so, and according to what Tessa told Stefan , each time a Petrova DG is born..a Silas DG is also born round about the same time ( for obvious reasons. How else could've all of them ended up together ?).
Confusion3) WHO share the epic 'universally-destined' love then? Statherine or Stelena? I think there's an explanation to that. Suppose, and I think I'm right.. The Salvatore line has probably come to an end. Which means, Stefans' probably the last doppleganger( this conflics with point 1 because if Silas and Amara doubles run in the same family...ugh, dilemma dilemma). Which means theres' hope Delena-shippers. Maybe Katherine and Stefan are supposed to end up together. I mean face facts, had Kathy not been such a bitch, Stefan would've still loved her and it's no secret that Kathy loves Stefie. But WTF happened to the SilasDouble born during Katherine's time ? Or the AmaraDouble born during Stefan's time ? And IF there were no complimentary doubles during either's time WHY, WHY ON IAN SOMERHALDER'S GREY EYES does once-scorned-forever-vindictive Tessa a.k.a Qetsiyah tell Stefan that ' It's always been the same. The dopplegangers have always ended up with each other or fallen in love'.
Brain just got fried after yesterday's episode.