No. The GOP would re invent itself, and bounce back no later than 2036, and the party would reinvent itself by either returning to it's 1952-76 days, or it'll become more libertarian.
2036? I think you're selling them short, they'd do better than that. If they didn't, they'll be replaced by a new opposition party.
Was the GOP replaced with a new opposition party after being defeated 4 times by FDR and again by Truman just 4 years later? Would the Dems have been replaced by a new opposition had Bush 41 been re elected in 1992 (which looked very likely through 1991 and even early 1992)? Based on history, and fairly recent history at that, I'm not underestimating them at all.