Question regarding blockchain-splitting features

[novusordo]

Could features that would split the blockchain (or bugfixes) be implemented in a way that they only take effect at a certain block number? I'm imagining it would be similar to how the block-halving works, but instead of a decrease in bitcoins the effect would be a feature or bugfix being enabled.

I would imagine that this approach could prevent a significant forking of the blockchain, if people were given enough (a lot of) time.

[DeathAndTaxes]

Yes.

It was already used in implementing P2SH. Miners could also indicate support by putting a "flag" in the coinbase field.  The block date wasn't set until the new version had 80%+ support from miners.  Even then the block date was put months in advance to give everyone a chance to upgrade.