In short, in my opinion there's no need for the migration. I have an explanation in a video, but it's in Bahasa Indonesia. It's here.
Now, back to the "euphoria" (if you can call it that). Would people start abandoning WA (WhatsApp) and switching to Telegram? Is it for good? I don't think it is happening. It's like abandoning Microsoft Windows for Linux.
Linux is as good as Microsoft Windows. (In my personal opinion, Linux is actually better, but this is from a techie person who have been using Linux since its early stage. I am biased.) Have you seen majority of people migrating to Linux? No. People are staying with Windows. Why? Because, we are used to Windows. Linux as a nice desktop too, but it is not as easy converting to Linux. Just not as easy as moving from WA to Telegram.
There is a "cost" of switching and it's not only about money. You already have a vast number of people in WA. This is a "network effect" issue. It is difficult to ditch them. And for most people in Indonesia, there is no privacy problem. Indonesians do not have privacy-concerned culture. (I should explain more about this.)
In the end, people are going to use WA. Just like people are still using Microsoft Windows. It's just a matter of time and calming process. Now, let's get back to our WA groups, shall we?