I doubt Trump will leave the party, far from it.  I think the real danger is down the road with changing demographics.  The GOP can get away with being a whites only party for a few more election cycles, but eventually unless they can find a way to do better amongst minorities they are in trouble.  Also Canada is a multi-party system thus why parties can come and go while US is a two party system so parties tend to change there rather than die out.  The death of the PCs is more akin to the marginalization of the Liberals in the UK who used to be one of the two main parties but are now a perennial third party.  They also like the PCs did merge with Labour dissidents in the late 80s who formed the Social Democratic Party thus merged to be the Liberal Democrats.