I would think it should. In English it's fine (minus the comma), if a bit flowery.
There is a very fine line between ‘flowery’ and ‘obsolete’. I don't think this sentence would even be considered correct in standard prose (in a period drama script or in poetry it would sound fine, I think).
English has not used this word order popularly in centuries. It's not wrong, it just sounds very poetic.
Because indirect questions are subordinate clauses (‘Nebensätze’, sg.: ‘Nebensatz’), so subordinate clause word order (verb-last) is in effect.
That's right -- it's inflected for the relative pronoun was.
Compare: Was wird passieren? to Ich weiß nicht, was passieren wird.
Or in English: "What is going to happen?" to "I do not know what is going to happen." -- no infinitive for "is going to"; it's third person singular, matching "what".
Someone can explain why wird is on end? All "relative clause" have verb on end? I dont know what is "relative clause" for english grama.
A relative clause is one that employs a relative pronoun or adverb, that is a pronoun or adverb that refers to an element in the previous sentence (antecedent) but is used instead of repeating that word. It may be clearer with examples:
in “everyone who knows you loves you”, “who knows you” is a relative clause where “who” is a relative pronoun referring to “everyone”;
in “I have a cat that never purs”, “that never purs” is a relative clause where “that” is a relative pronoun referring to “cat”;
finally in “I remember the place where we met”, “where we met” is a relative clause where “where” is a relative adverb referring to “the place”.
Relative clauses are by definition subordinate clauses (“Nebensatz”, pl.: “Nebensätze”) and as such follow verb-final word order.
Great explanation however a bit confused on what is the relative pronoun or adverb here?
was is the relative pronoun.
The thing it refers to is not explicitly mentioned -- "what will happen" is more or less equivalent to "the thing that will happen" but "the thing" is not mentioned.
was passieren wird is a (headless) relative clause -- and relative clauses are subordinate clauses, and those have the verb at the end in German.