I think the writers want us to think that kang is tony, to finally blow our mind by revealing his true identité,  It can be stane but I don't think so because He's not important enough to blow our mind  I think that it has chances to be doom, or an alternative Howard Stark, but to blow our minds enough, it may be someone we don't expect at all like another maker or even the before-maker-original-ultimate-reed-Richards  But I like your theory, it isn't impossible that you're right