ESA50 Returned - Short Term Support Group Award

I have been in the Contributory ESA Support Group for around 8 years now approximately. Recently I received my ESA50 form to review my entitlement. This was completed and I received quite a rapid response back stating that I was to remain in the Support Group. I did not have to attend a medical assessment at all. I was happy with the decision and could breathe easy once again for a while.
The problem I have with this is the relatively short term this is for. The payments are only for a period of around 15 weeks, until around the end of November. My ESA50 was improved in some circumstances and worse in other areas. So in my view not a lot of change to note.
I am at a loss as to why this is only for this short period of time. Why is the period of award such a small amount of time? Anybody got any ideas? I have had no problem in the past with it. What happens at the end of this period? Do they write to me again with the same form for completion once again, or God forbid would they stop the award, either in whole or in part?
I aim to hopefully go back to work eventually, but certainly I am not ready for it within the foreseeable future just yet!
Any advice or reassurance would be gratefully received. I am panicking already with the thought of it being stopped.
I am also waiting for a decision from a PIP continuation medical assessment if that has any relevance to this situation.
Many Thanks.

Thank-you very much for your rapid, kind, knowledgeable response once again Gordon.