Possibly, but here, quotes from an interview:
"Well, I swapped him for someone else, and I don't want to say who for the people who haven't-- read. But I-- I made a decision as I went into writing Phoenix that I was going to reprieve Mr. Weasley and I was going to kill someone else. "
"But-- so there are two characters who are killed in (book) Seven. So Mr. Weasley did get attacked, as you know, in Five. But he would have died if I'd have stuck to the original plan. But he survived. "

So even if JKR wrote him somewhere in the back of her mind just to kill him off, it wasn't part of the original plan. (Why did she have to make him so loveable?"

But this is the mad and angry and mourning side of me talking, maybe. I'm not entirely sure anymore.