At the very end...

I think it just means that he's going to visit the memorial again in 2 days... that's all I can think of... unless he knows that he's going to die in 2 days, but that's unlikely

"The world moves for love, It kneels before it in awe" - The Village

My first language is Mandarin. He says “过两天再来”, which literally means "come after two days", but it's really just an expression of I'll be back again soon or I'll see you again soon. It's sorta like "one second", you don't really mean you'll take only one second.

TL DR: Actual translation means I'll see you again in two days, as in he'll come visit the memorial again soon.

Who the hell was that guy in the end?

did I miss something?

I've just watched this on television.
The subtitles that appeared read;

"I'll come to visit you again"

I thought the reference meant that he would visit again in two days...as he did two days before that...and two days before that...and... Which means he never forgot his loved ones and never will - so much so that he returns to the memorial on such a regular basis to show the depth of his love.

As spoken by Mr Song at the end of the film: "过两天我再来看你。"
=> Literal translation: "After 2 days, I will come again to see you."

https://translate.google.com/#zh-CN/en/%E8%BF%87%E4%B8%A4%E5%A4%A9%E6% 88%91%E5%86%8D%E6%9D%A5%E7%9C%8B%E4%BD%A0%E3%80%82
As translated by Google: "I'll see you in two days."

The above might simply mean that he is planning to visit the memorial — or rather, the memory as represented by the inscribed names of his lost family members — again in 2 days' time.

However, in Chinese, "过两天" ("after 2 days", "2 days later") is also a colloquial expression implying "soon" or "in the very near future" — & not necessarily referring to a fixed number of days.

"再" means "again". This implies that Mr Song has been visiting the memorial on a regular or periodic basis. As such, his entire statement has nothing to do with (his) impending death or suicide, as some might have thought.

A similar but more succinct expression would be: "过两天再见。" — meaning: "See you again in 2 days." or "See you again soon."