It was a different political climate in 1982. Just because a republican retires does not mean that a Democrat will win that seat. A Republican dist will just elect another Republican.
I don’t think the Pubbies losing the House is necessarily a disaster for Trump, if anything, making the RINOs irrelevant may clarify things and clearly puts Trump against the Democrats, without the RINOs getting in the way.
And forget all that garbage about Impeachment, it’s not happening.
I remember 1982 pretty well. It was a different political climate back then. The Republicans and Democrats actually got along with each other. Ronald Reagan and Tip O'Neil were best buddies.
Also, the economy was still in its doldrums in 1982. The Reagan economy was just starting to gather some steam but too late for the mid-term election cycle. Things still looked pretty bleak economically speaking.
You are right, a Republican retiring from Congress does not automatically result in a Democrat getting that seat. It might actually work to our advantage - getting a lot of new blood into Congress.
Imagine what can get done if Republicans have majority in Congress after all that turnover. Could very well happen. Do not underestimate Trump's ability to get out the vote. I see a lot of Trump rallies this coming summer and fall. If the economy is still roaring, the Democrats will be on the defensive and as of today, they still have no plan except hating on Trump.