True but they will have a hard time ignoring the 22nd amendment of the US constitution and it would be an easy move to remove him from the election process which a majority of the states themselves could do without opposition.
They might try the good old Putin trick, have a puppet elected on behalf of Trump and let Trump have another high-ranking position (e.g. Vice President) and hold the real power. Trump can still do most of campaigning, and there is also ample opportunity for election fraud.
Each state can decide to not list him in the election process. Some red states for sure would but plenty would not including a few red and purple states.