Jerry Lee Lewis was poised to be one of the first white rock and roll superstars until his career was rocked with scandal. Had that happened it is very possible that the piano would become the predominant instrument in white rock.
The genre already has its roots in jump blues and boogie woogie, both piano driven styles. Little Richard and Fats Domino were at the top of the charts.
Had a piano player been the king of white rock then you would have likely seen a lot more artists picking up that instrument rather than the guitar.