The thing I worry about the most is that Go without generics works very well for 95-99% of code. The code is very clear and not overly abstract. The remaining 1-5% of code is hard to write in an efficient, type safe, and DRY way, but I don't see how we can have generics and clear, appropriately-abstract code. I strongly suspect this will change the quality of the ecosystem for the worse. I don't think people consider this tradeoff very often.