Almost, but not quite

I see your point but each individual state does decide now how their electors are selected... 48 of the 50 states have decided on a "winner-take-all" approach to selecting the electors...

You're confusing how electors are selected with how they are required to vote. It doesn't matter how electors are selected. They could be popularly elected, appointed by the legislature, or picked by lottery, the point is, there must be no requirement or restriction on how they vote. And if there is no popular election for President, there can be no "winner-take-all" rule.

I actually favor this method.

Then you favor democracy in picking the executive and the end result will always be the same one we know now.

...how can we repeal the 17th amendment when our state legislative districts are gerrymandered like they are?

Gerrymandering will always exist. The question is how badly gerrymandered the districts will become. One of the reasons that gerrymandering occurs at the level it does now is that the state legislatures have been reduced to junior version of the Congress. That was never the founders' intention. Repealing the Seventeenth Amendment would necessarily make the selection of state legislators more serious, especially in states where Presidential Electors were selected by the state's assembly.

In any case, both parties gerrymander, so that plays no role in whether or not Senators should be popularly elected or not. It is the same kind of minor complaint as the one used to push through the Seventeenth in the first place. Partisan politics deadlocked state legislatures and some states were going without Senate representation, sometimes for years. That is not a problem with how Senators are elected, that is a problem the people need to correct in their legislatures. If their state goes long enough without a Senator, I expect they'll empty the state legislature and get a group elected that can do the job.

At that time they weren't necessary, but I believe they are now.

Only because you have acquiesced to democracy. Term limits are not necessary in a constitutional republic. Term limits are an implicit admission that the people are not qualified to select their leaders. That is absolutely true, but limiting the terms of elected officials is only treating the symptom, not the problem. The solution to the problem is republic, not hobbled democracy.