Approval ratings three years out from the election and in the absence of other party leaders and platforms for the 2019 election mean nothing.

Trudeau 1.0 also had high approval ratings after his first year in power - and this was against both the Conservatives and the NDP with capable leaders and partial platforms - but by the time of the next election in 1972 his approval ratings were down so low that he only won by two seats in a minority parliament and only then because Quebecers voted tribally.

So even if The Clown Prince's ratings are still high, it doesn't mean a thing.  (There is no opposition yet and only political wonks like you and me are paying much attention this early on.)