Henry Ford II, around 1952, cut prices on all Ford cars in an assault on GM; GM and Chrysler responded in kind, but the independents couldn't. They all withered and died, though Nash/American Motors struggled for decades. If Ford hadn't embarked on this futile, costly course of action, might all these cars have survived? (Perhaps not until 2008, given the state of GM, Ford & Chrysler in this TL?)
I think you'd need an earlier POD for some/all of the so-called postwar independents to have survived. Interestingly, Ford was in such dire straits in the late 1930s that there were serious negotiations with Studebaker that, if consummated, would have had Studebaker owning Ford outright. Setting that aside, had there been a move to merge in the years shortly after World War II, it's not impossible that there would have been a fourth major player in the US automotive industry, with Packard, Hudson, Nash, Studebaker, Willys and possibly Kaiser/Frazer under one umbrella.
Packard would have provided excellence in engineering; Kaiser/Frazer the production know-how; Studebaker, a long-standing tradition of client loyalty and significant capital; Hudson and Nash, styling prowess. In that lineup (let's call it US Motors for convenience, you' might have had these matchups:
Packard / Cadillac / Lincoln / Imperial
Frazer (probably would have been sacrificed early; the pre-war LaSalle was about as close an analog as one might get)
Hudson / Buick / upper end of Mercury / Chrysler
Nash / Oldsmobile / lower end of Mercury / De Soto
Kaiser / Pontiac / upper end of Ford / Dodge
Studebaker / Chevrolet / lower end of Ford / Plymouth
Willys probably would have continued as a sub-Chevrolet no-frills make (I doubt that there would have been a Henry J) or would have disappeared leaving only Jeep as perhaps a separate division.
Ford might have forced the Edsel a few years earlier to work against Nash, De Soto, and Oldsmobile, but for the most part, I think these days, Ford would be bringing up the rear, concentrating largely on trucks, entry-level cars (Focus), quasi-senior citizen cars (Crown Victorias without the police interceptor package), and police cars. Given Ford's propensity for derivative styling, lagging in engineering (don't forget Fords had mechanical brakes late in the 1930s, years after everyone else had gone hydraulic), and doing things differently just to be different, today we might be speaking of Daimler-Ford, with Ford clearly the junior partner.