Not really, no. UK is number 22 in population, so being #16 in economy would still make it above average.
Given how Brexit looks like UK will be overtaken by France, India, Italy, Brazil, Canada, South Korea, Spain, Mexico and Indonesia in that time for sure, there is no way around that. That would make it #14 and we've only spent the countries that will outgrow UK without a doubt. Add in a few wildcards - Turkey, Australia, Argentina, Taiwan - and UK will have to count itself lucky to even be in the top 20.
McHrozni