ICC hasn't been as conservative as people like to believe. They have and are changing rules in order to accommodate more teams and making Cricket a global sports. They have increased the number of ODI teams from 10 to 20 with 8 spots for grabs by any associate teams with a long league with promotions and relegations. T20 are more generous with International status provided to all teams. So, T20 and ODI are already a merit based format. Test is a more traditional format that still needs change. The less interest in changing the test status might also be due to it being the least popular among the three formats and it takes days for a match to complete. Yet, they might extend the Test world championship to a top level league and crate a lower league that accommodates all ODI teams in the future.
ICC is changing cricket rules to make sport global especially in ODI and T20 formats which are now more open to many nations. Idea of merit based system like in football is great way for smaller teams to rise to top. Test cricket is harder to change because it is so long and traditional as we know its take 5 days. However adding lower league to Test Championship will give more teams chance to play and make format more popular.