It’s incredibly frustrating for many of us, but smartthings have still not put out an official response as to what will happen with virtual devices. 
Right now there are five ways to create virtual devices.
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using the virtual device creator wizard in the smartthings app on android devices. (It’s not available on iOS devices.)
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use the groovy stock device type in the IDE.
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use a custom groovy DTH through the IDE.
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use a custom edge driver.
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use @lmullineux ’s simple device viewer to created a cloud-based virtual switch on the new architecture. Unfortunately, these can’t trigger an Alexa routine, but if you just want a simple virtual switch, maybe to proxy something else, it’s a good option that will work even after groovy goes away. Or if you need one of the other kind of cloud-based virtual devices available through this method.
Right now, the main method that we know will work after groovy goes away is option 4, custom edge drivers. There are several of these. All of them seem to be good so far, each has different features. And there is also option five, which doesn’t require a hub. You can find them by checking the quick browse lists in the community – created wiki and looking for the list for virtual devices. 
https://thingsthataresmart.wiki/index.php?title=Quick_Browse_Lists_for_Edge_Drivers
But what if you created your virtual device on the old platform? The answer is we have no idea what’s going to happen with these. 
Although the question has been formally asked many times. We don’t know if they will be transitioned or abandoned. We don’t know what will happen to routines that use them.
We do know that staff members have asked people who raised the issue if they created the virtual device through the wizard in the SmartThings app or through the IDE, but then there was never a follow up response to say what difference that might make.
We also know that under the old architecture, you could create virtual switches whether you had a smartthings/aeotec hub or not, and quite a few people did. But edge drivers only work if you do have a hub.
The question has been specifically asked whether after groovy goes away there will be a method for people who don’t have a hub to create virtual devices, but again, no answer yet.
As @Paul_Oliver notes below, @lmullineux recently added A virtual device which is cloud-based, so you won’t need a hub. But you also can’t use it as both a switch and a sensor so you can trigger an Alexa routine. (This is what people mean when they say “Alexa switch”— A dual capability device.)
So if you do have a hub, the safest thing right now is to replace any virtual devices you have with method 4, choosing one of the edge drivers for virtual devices. But that could be a lot of work and you might not need to do it – – we just don’t know yet! And that option is not available to those who don’t have a hub.
I myself have been asking this question formally for almost a year now. I don’t understand why there isn’t yet an answer, so if I’ve just missed one, I hope someone will post it. But so far I haven’t seen it.