Today, most railways around the world (about 60% of rail trackage worldwide) use so-called 'standard' gauge, where the tracks are separated by 1435 mm of space, including virtually all railways in the United States, most of Europe, and China. Some countries, such as Russia and India, mostly use broader gauges however, and broader gauges were often used in countries which today use standard; for example, Brunel famously used an extremely broad gauge of 2140 mm for the lines of the Great Western Railway, and many lines in the United States used a variety of broad gauges early on.
However, aside from a relative handful of countries where broad gauges stuck, most of these lines in countries that otherwise used standard were eventually converted to standard gauge. The Great Western built an increasing amount of standard gauge track and eventually abandoned broad altogether, while American lines using broad gauges were generally converted to standard in the 1870s and 1880s. How could this be changed so that a broader gauge becomes considered 'standard,' such that more than, say, 50% of world trackage is in this gauge? For the purposes of this question, any broader gauge, from Russian (1520 mm, so not that much broader than standard) all the way up to Brunel's 2140 mm gauge counts. And, supposing this is done, what would the effects be?