If Intel pulls off DSA, they will be using a newer generation of technology compared to TSMC using an optimized older generation. Could TSMC still make better chips? Maybe. But Intel will likely be better.
Dsa is one of many patterning assist technologies, just...an old one. Neat, but not 'new'. You use patterning assist to make smaller, more regular features, which is exactly what the 16a vs 18a refers to.
That has somewhat less to do with performance, which is tied as much to material, stress, and interface parameters. Nothing gets better from being smaller in the post dennard scaling era, the work of integration is making better devices anyway.
Patterning choices imply different consequences. For example,.a.double euv integration can take advantage of spacer assists to reduce ler and actually improve cdu even with a double expose. Selective etch can improve bias, spacer trickery can create uniquely small regular features that cannot be done with single patterns. Conversely, overlay trees get bushier, and via CD variance can cause horrific electrical variance. It is complicated, history dependent, and everything is on the developmental edge.
To the best of my knowledge, DSA never made it out of the lab.
Is Intel working on "an optimized older generation" as a backup plan? I don't follow semiconductors very closely, but my impression is the reason they're "behind" is they bet aggressively on an advanced technology that didn't pan out.
If that's the actual root cause, then Intel's lagging is due to optimizing their balance sheets (investors like low capital expenditures) at the expense of their technology dominance.