Can I blend Future Perfect and future-in-the-past?

Question

Can I blend Future Perfect and future-in-the-past? For example,

He would have served the remainder of his term and leave office in 1990.

It may be confusing since the "would have" structure is also used in the 3rd type of conditionals so the sentence could be misinterpreted (not that he did serve it completely, but that he could serve it if some conditions were met but didn't, at least if the sentence didn't have the second half). The reason I don't want to simply use future-in-the-past is I want to stress that the action was completed.

Answer 1

I can't see a way to mix and match like that.

You could have a counterfactual with "would have served... (would have) left" like this:

If he had not been ousted, he would have continued in office. He would have served the remainder of his term and left office in 1990.

Or you could describe the real outcome with "would serve... (would) leave" like this:

His enemies had failed to oust him. He would serve the remainer of his term and leave office in 1990.

Answer 2

He would have served the remainder of his term and leave office in 1990.

is the exact equal of this:

He would have served the remainder of his term, and he would have leave office in 1990.

As you can see would have leave is not a known grammar structure in English.

You change it to

He would have served the remainder of his term, and he would have left office in 1990.

or you can combine the two sentences with the and :

He would have served the remainder of his term and left office in 1990.

Answer 3

He would have [or could have] served the remainder of his term and left office in 1990.

would have or could have goes with both verbs but you don't have to repeat it.

Same idea: I have seen the movie and [have] been to the beach.

He would have eaten ice cream and [would have] drunk beer too!

There is no blending:
He would have served
he would have left

But: no need to repeat "would have".

In compound verb phrases, there is no need to repeat the modals and auxiliaries. You only repeat the past particple.