Hi @regi_p !
You already said it - since 5700 switches run without any single issue, why there should be a new release? To fix what? Also, keep in mind this note - https://techlibrary.hpe.com/us/en/networking/products/eos/index.aspx#item8 It means that currently our devs will be focusing on bugfixes and security updates for this product, not new features. And as a Support Engineer let me share with you some inside - there are no many calls about 5700, it is pretty mature product. And despite the fact there is newer generation - 5710, the 5700 series still have pretty decent performance as ToR switches and suit networking needs of many customers. Thus if it suits your needs and you are happy with it - there is nothing to worry about. Of course, if you encounter any issue with your 5700 - just give us a call, open a case with HPE Support and we will be happy to assist you.
Hope this helps!