There are the obvious big contenders Java and .Net which will exist in some capacity for a long time due to the volume of code running on them. But will the we

There are the obvious big contenders Java and .Net which will exist in some capacity for a long time due to the volume of code running on them. But will the web based UIs based on today's standards even work in 20 years? And will data exchange formats like XML and JSON necessary for their operation still be common enough to make the applications that use them useful? Will the use of cutting edge web based UIs, using CSS and and JavaScript libraries like JQuery damn our users to a world of legacy browsers like what happened with IE6?