This is a far away task. Mainly because of Java 11 only available in 64-bit version. We can probably have installers with Java 8 32-bit and Java 11 64-bit, but that would be a nightmare to maintain, especially given nearly non existent maintainers/developers for Spark. We can still provide only Java 8 bundled installers until it is supported by Oracle (till the end of 2020) and then think about switching to 11.
There is also uncertainty about licensing. Maybe will have to bundle with OpenJDK or not bundle at all.