Problem
My share servers are not visible in the Windows explorer anymore.
Solution
If you really need network discovery, WSD is what you need. The good old networkdiscovery will not come back for security resons.
WSD is not part of samba and it will be not implemented.
Check if the use of mapped network drives deployed by GPO is also the best way for you. It is the motly common recommendation.
A good explanation about loosing that feature you can find here.