Thanks for asking.
Both classic and V2 elements offer certain value proposition. On one hand V2 elements gives you more flexibility regarding customization without the need of CSS. On the other hand, classic elements are quite simple to use but don't offer much of GUI based options in terms of styling the elements and more often then not you will have to write some CSS to make changes. That being said, we are not going to disable the classic elements.
If someone has used classic elements i past, they are free to continue using classic elements. However, if they want more flexibility then ofcourse one can take advantage of V2 elements.
For a fresh website, again it depends on the requirements. If I were to design a new website I would use V2 elements as it offers better flexibility.
To get started with V2 elemetts, I suggest you to please take a look at our KB section.
I am sharing few more resources that you can take a look to get started with V2 elements.