In the LCD screen world you can get;
UXGA (1600x1200) with a standard 1.33x aspect ratio screen, in sizes of 14.1, 15.0, and 16.1 inchs.
WUXGA (1920x1200) with a widescreen 1.60x aspect ratio screen, in sizes of 15.4 and 17.1 inchs.
As far as the current crop of Toshiba laptops go, the highest resolution I've seen in their standard screen sizes of 14.1 and 15.0, has been resolutions of up to SXGA+ (1400x1050), like with the Portege S100 and Tecra S3 (and others). In terms of widescreen, rodarapan is right. The only WUXGA laptop screen Toshiba has is on the G35-AV650 Qosmio, at 17.1 inchs. You can also get 17.1 inch WSXGA+ (1680x1050) on the P100 BTOs, P100-ST9412, and P100-ST9612. You can also get 15.4 inch WSXGA+ on the Toshiba Tecra A7 BTO.
So in terms of your original question. I don't think that Toshiba will produce a new laptop offering with a 15.0 inch UXGA screen. SXGA+ seems where the industry "sweet spot" has topped out with 15.0 (and 14.1) inch screens. And as has been pointed out, Toshiba already produces one laptop with a 17.1 inch WUXGA screen. I would guess that in the future they may expand this, as other laptop manufacturers have started to supply these types of screens on their 17.1 inch laptops, more readily. I also expect that laptop manufacturers will start providing more WUXGA 15.4 inch screen choices. As to whether it's Toshiba, who knows? Maybe it will be a BTO option in the future.. All obviously IMO only..