The size of the block reward is irrelevant when the coin itself is worth nothing in fiat terms ie. purchasing power. Miners can't pay their running costs and hardware based on the arbitrary number that is the size of the block reward.
The only reason why the upcoming difference in block reward between BTC and BCH / BSV is relevant at all is because we're looking at running systems sharing the same mining resources with a somewhat stable equilibrium that will soon be broken. For all we know BCH / BSV might as well manage to offset their premature halvening by doubling their value relative to BTC.
Let's hope they do it. It would make a good example that the Core developers' design-decisions, and Bitcoin's model is far more superior and robust.
Regardless of that I'm looking forward to see the first coin apply sharding to cryptocurrencies. Be it Ethereum, be it a Bitcoin fork or be it something else entirely. I personally doubt that blockchain sharding is the scaling solution that some people make it out to be, but the worst case that can happen is a learning experience for all.
Then do it on Ethereum in my opinion.