It only shows a '∞' for the gateways.
And there will always be new coins that will need new gateways, so that figures.
Yes, it shows a '∞' symbol for the gateways.
But, 'smart-contracts' time-frame equal to 'gateways' time-frame on the roadmap

So we can assume that there is no plan to finish 'smart-contracts' at all.
Development of the Sigma script language for non-Turing complete smart contracts will start in Q1 of 2018.
It is expected the first mainnet release will be in Q2 / Q3 of 2018.