If he had lost today, he might have needed a semifinal to be sure of qualifying, but that question is moot now with him in the Basel final
Current Live Race points, which would also reflect a Federer Basel loss in the final:
3445 Federer
3150 Wawrinka
3120 Gasquet
3055 Tsonga
2770 Raonic
2415 Haas
Paris projections:
.............R64(10).....R32(45)......R16(90)......QF(180).....SF(360).....F(600).....W(1000)
Federer.....3455..........3490.............3535.............3625.............3805.........4045..........4445
Wawrinka.3160..........3195.............3240.............3330.............3510........3750..........4150
Gasquet...3130..........3165.............3210.............3300.............3480........3720..........4120
Tsonga....3065..........3100.............3145.............3235.............3415.........3655..........4055
Raonic.....2780..........2815.............2860.............2950.............3130.........3370..........3770
Haas........2425..........2460.............2505.............2595.............2775.........3015..........3415
If Federer wins the Basel final, he is assured of a spot with 3645 points (add 200 to all his points above) without playing in Paris, because only 2 players can reach a final and possibly surpass Federer, and that would automatically give him the last spot.
If Federer loses the Basel final, then the projections are as above. For Federer not to qualify, due to the Paris draw, Raonic must win in Paris and beat Gasquet in the semifinal, and Wawrinka would have to either advance to the final and Federer would have to lose prior to the semifinal, or Federer would have to lose prior to the round of 16 and then Wawrinka would only need to make it to the semifinal.
Chances of this happening? Pretty slim I think.
Oh, as one can see, Tommy Haas can no longer surpass Federer, though he still could potentially qualify with a win.
Respectfully,
masterclass