If flex q is still around by next year, if you have silver in solo and gold in flex q, what border

both. gold when u play flex and silver when u do solo

Like this year (and ones before it), you get the border appropriate to the queue type, and it generally works that it's the best across any queue that shows up in normals/FGMs. I've been in queue with a handful of people with challenger borders who were plat/diamond in solo queue, but since they were challenger in rank 5v5 they get to show up the fancy border.

So next year you would have a silver border when playing solo/duo, a gold border when playing flex, gold border in normals, and gold on your profile and most other places. I think you'd be borderless if you did TT games though unless you achieved a rank in ranked flex 3v3s.

There's a support article that talks about all the different borders for different modes as they show up this year if you look into it.

edit: Ok from the preseason FAQ. Similar rules will inevitably apply next year.

Loading Screen Borders

Part of your season rewards package is a loading screen border. Your new border will be visible once you receive your ranked rewards. There are a few new queues this season, so here’s where your borders will appear:

Ranked Solo/Duo - 2016 Dynamic Queue Ranked Flex 5v5 - Best of 2016 Dynamic Queue or Ranked 5s (not available until Patch 6.23) Ranked Flex 3v3 - 2016 Ranked 3s (not available until Patch 6.23) Normal Summoner's Rift - Best of 2016 Dynamic Queue or Ranked 5s Normal Twisted Treeline - Best of 2016 Dynamic Queue or Ranked 3s Co-op vs. AI Summoner's Rift - Best of 2016 Dynamic Queue or Ranked 5s Co-op vs. AI Twisted Treeline - Best of 2016 Dynamic Queue or Ranked 3s Custom - Best of any 2016 queue Rotating Game Modes - Best of any 2016 queue ARAM 5v5 - Best of any 2016 queue

As far as I know, it'll use your solo/duo border for anything that's not flex queue.