I assume you meant DNSsec key, not "DANE key"? (No such thing, anyway.) For this discussion to make sense, it has to be the TLD's DNSsec ZSK or KSK.
The fix in either case is key rollover; if it's the KSK it needs to go to the root which will be annoying but doable. The TLD needs to do this, and it'll be complete, for everyone, regardless of updates or shitty devices, after the relevant TTL has passed. The TTL on the root zone's DS records seems to be 1 day.
If the TLD fails to do the key rollover for whatever reason (incompetence, maliciousness, …) - DNSsec is now broken on the entire TLD. So, security of DNS fails down to classic DNS with all spoofing problems and randomization/uniqueness countermeasures we've accumulated over 35 years. Their DNSsec signatures are still valid, DANE is still green. It really depends on your stance on this; personally speaking I'd consider the TLD unusable now and end the post here, but I assume you don't share that view.
Can you spoof/break DANE now? Yes, if you can break DNS. But in that case, you're in a whole lot of trouble already; if you can really break DNS (poison arbitrary resolvers) you can now get a 'classic' (non-DANE) TLS certificate from your favorite ACME provider. If you can't fully break DNS, that essentially leaves MITM situations, i.e. specific individual situations. Part of that is getting improved with DoT, DoH and DoQ (which, yes, have their own issues.) Realistically, browsers would be marking the entire TLD DANE-untrustworthy now.
On Earth-666, you could presumably roll out DLV [DNSsec Lookaside Validation] now — that's the "side root" mechanism that was used before DNSsec became ubiquitous at the TLD level. Most DNS people absolutely hate it. Ignoring that, the one TLD is now screwed and it's a layer 9 fix. Is that better or worse than a compromised CA resulting in every single TLS service being screwed? Neither, just different, I'd argue.
(As batshit crazy as it is, maybe DLV is the answer to the kind of compromise you have in mind. You seem to be happy with browser vendors having a lot of authority and control over trust. A browser could unilaterally decide to roll out DLV on a given TLD, or any level of domain really. Somebody has to run that as a service, though. Unless they ship the records with the browser… but that's getting really extreme now.)
For the sake of useful discussion, another case to consider is a malicious TLD that specifically hates you. (Or was given reason to hate you by legal means.) They can publish completely bogus data for your domain, including DANE records. But they can also get ACME certs… so I'd call that a wash. (Sure, they wouldn't be able to get OV certs. But a situation with OV certs is IMHO also a situation where you wouldn't use DANE exclusively, rather you'd require both DANE & classic PKI.)
The fix in either case is key rollover; if it's the KSK it needs to go to the root which will be annoying but doable. The TLD needs to do this, and it'll be complete, for everyone, regardless of updates or shitty devices, after the relevant TTL has passed. The TTL on the root zone's DS records seems to be 1 day.
If the TLD fails to do the key rollover for whatever reason (incompetence, maliciousness, …) - DNSsec is now broken on the entire TLD. So, security of DNS fails down to classic DNS with all spoofing problems and randomization/uniqueness countermeasures we've accumulated over 35 years. Their DNSsec signatures are still valid, DANE is still green. It really depends on your stance on this; personally speaking I'd consider the TLD unusable now and end the post here, but I assume you don't share that view.
Can you spoof/break DANE now? Yes, if you can break DNS. But in that case, you're in a whole lot of trouble already; if you can really break DNS (poison arbitrary resolvers) you can now get a 'classic' (non-DANE) TLS certificate from your favorite ACME provider. If you can't fully break DNS, that essentially leaves MITM situations, i.e. specific individual situations. Part of that is getting improved with DoT, DoH and DoQ (which, yes, have their own issues.) Realistically, browsers would be marking the entire TLD DANE-untrustworthy now.
On Earth-666, you could presumably roll out DLV [DNSsec Lookaside Validation] now — that's the "side root" mechanism that was used before DNSsec became ubiquitous at the TLD level. Most DNS people absolutely hate it. Ignoring that, the one TLD is now screwed and it's a layer 9 fix. Is that better or worse than a compromised CA resulting in every single TLS service being screwed? Neither, just different, I'd argue.
(As batshit crazy as it is, maybe DLV is the answer to the kind of compromise you have in mind. You seem to be happy with browser vendors having a lot of authority and control over trust. A browser could unilaterally decide to roll out DLV on a given TLD, or any level of domain really. Somebody has to run that as a service, though. Unless they ship the records with the browser… but that's getting really extreme now.)
For the sake of useful discussion, another case to consider is a malicious TLD that specifically hates you. (Or was given reason to hate you by legal means.) They can publish completely bogus data for your domain, including DANE records. But they can also get ACME certs… so I'd call that a wash. (Sure, they wouldn't be able to get OV certs. But a situation with OV certs is IMHO also a situation where you wouldn't use DANE exclusively, rather you'd require both DANE & classic PKI.)