Hey @Sergey Litvinov ,
Currently, we do not have an ETA on .NET 4.8 support for Azure cloud service classic. However, we would love to know your use case in order to be able to share this feedback with the product team. Please feel free to share your use case and provide specific details in an email to azcommunity@microsoft.com along with a link to this post, with Subject - 'Attn: Winston' so it gets routed to me.
Thanks!