Can the 的 particle ever function without "nominalizing"?
You can find the answer in 百度百科 using the key word 语气词 in Baidu search.  Here is the quote relevant to your question:

普通话里最基本的语气词实际上只有六个：的、了、呢、吧、吗、啊。其他一些，有的用得较少，有的是因为语气词连用而产生连读合音的结果，例如“啦”是“了啊”的合音。这六个语气词根据在句子里出现的先后次序可以分为三组，

It has a table listed all the usages of those 语气词.  I can't copy the table from my mobile device. But it has this example 我不会忘记你们的。to illustrate the usage of the 语气词 的.
It's written in Chinese though.  You can try to understand it using a translation tool.