Either Toyota GT-86 or Subaru BRZ Getting Convertible

You can not expect ToyotaToyotaJapan, 1937 > present155 models
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and SubaruSubaruJapan, 1953 > present34 models
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to spend unknown billions of yen to develop the Toyota GT86Toyota GT 86Japan, 2012 > present9 photos
/ Subaru BRZSubaru BRZJapan, 2011 > present7 photos
and not develop variations on the platform. It appears that the first variation of the car will be a four-seat convertible version.

Adding a convertible version will mean that Toyota and Subaru can sell a few more of the sports coupe and hopefully it will be around longer. It will also directly compete with the Mazda MX-5 MiataMazda MX-5 Gen.3 [NC]Japan, 2006 > 201448 versions
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in terms of power, price and be close to it in weight. 

The convertible would use the same 200hp, 2.0 liter boxer four-cylinder engine with the same automatic and manual options.

Weirdly, the convertible might be even more competitive in the market than the coupe. Its price would be higher than the coupe, but probably still under $30,000. That would make it among the cheapest four-seat convertibles in the US. Both the Fiat 500Fiat 500C LoungeItaly, 2011 > present2 photos
and the MiniMINI (BMW) Cooper Convert...Germany, 2008 > present2 photos
are available as four-seat convertibles for less money, but the BRZ/GT-86 has very different driving dynamics than those two cars. 

The earliest that the convertible would be available would be late 2013 or early 2014.

There are other rumors about the future about the car's platform. One is that Toyota is considering using it for future models including the next generation Lexus ISLexus ISJapan, 1998 > present3 series
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. The other on-again, off-again rumor is that there may be a turbocharged model eventually. 

Source: Car and Driver