4.99 generation fighter

Given the first flight of the T-50/PAK-FA, should “Western” countries other than US (who has F-22) implement a rapid-development 4.99 generation fighter to directly counter export market PAK-FAs which may start appearing as soon as 2018-2020?

1 time payment joint funding from:
UK
Australia
Canada
Japan
Israel
Singapore
Poland
Ukraine
+ “export” market.

For rapid development BAE Systems seems best qualified to lead without politics and consortium slowing things down.

Wouldn’t have to be ‘better’ than PAK-FA or F-22, just keep skin in the game.