Thank you for your question!
In the cycle of time which lasts 5000 years according to this knowledge, what we see is entropy increasing little by little. For “learning purposes” those 5000 years have been divided in 4 ages. However, see that this division is “artificial,” for there is no point where we can say “here it is” this is a “new age” and everything is different now. Everything changes little by little like a day changes into night time.
Now, Samgamyug or the “confluence age” (as it is translated in English) typically is known as the confluence between the Iron age and the Golden age, but it can also very well be between the Silver age and the Copper age. That is another “confluence.”
Your question refers to the former, iron age and golden age. Sangamyug only exists for Brahmin souls. (Also between the Silver age and Copper age as you can see for those “deities” there where Brahmin souls as well at one point of the cycle of time.)
Therefore, as long as the Brahmin clan exists at this time, there will be Sangamyug.