GST number will be PAN based and PAN is mandatory for getting registration.
However I don't think government has intention to make Aadhar compulsory for GST. They have not made it yet.
Anyhow you need to connect your PAN with Aadhar and also you need to have a Aadhar to get new PAN card.
So indirectly whether they make it compulsory or not your PAN and Aadhar will be linked through Income tax website if already having pan or if applied for new PAN you need to provide Aadhar.
It will not be difficult for government to track each and every business or person through Aadhar. Everything is linked to Aadhar.
chatCommentsThat makes sense. Already PAN is linked to Aadhar, so anything that needs PAN automatically gets linked to Aadhar. - Rahul Rai