CTV's strongest use case is congestion control. This doesn't reduce the amount of on-chain txs, it actually increases them but you can delay broadcasting the outputs. This can help smooth out fee spikes but does not increase throughput.

Ark broadcasts a tx every 5 seconds. Each ark service provider multiplies this number. That's a lot of transactions.

Other UTXO sharing schemes need to be unwound somehow. For a unilateral exit this usually means multiple transactions. Same dynamics play out in lightning with only two channel peers. Imagine having 10 or 100 UTXO sharing peers. Unwinding that will take a lot of block space and you probably won't get to pick the timing.

Covenants are going to supercharge the value you can get for your block space. But I think this will make it more scarce, not less.