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While tourism and air transport are recovering from the impacts of the Covid pandemic, it seems timely to draw a synthetic view of future stakes combining the following topics: the greenhouse gas emissions scenarios for tourism, regarding which recent work has improved their understanding; the climatic impact of aviation, almost 60% of which is due to non-CO2 emissions; alternative fuels (biofuels, E-fuels, hydrogen) and engine designs (fuel cells...) which are complex and controversial issues, and whose potentials should be assessed regarding their timing, environmental impacts, and their ability to meet long distance travel requirements. This paper analyses the extent to which the new options regarding fuels and engines can help decarbonize tourism and air transport. The answer is that they can partly contribute but do not render obsolete previous work on substitutions between types of tourism (short versus long distance...), between transport modes (ground transport versus air), length of stay, etc. Following this step, the paper deals with the position of aviation players and the type of arguments they use. We conclude on the necessity to make strategic choices among the options to avoid wasting investments.