If something happens with their servers and they shut down, you should import seed words in other wallets that use same BIP format.
However, some problems may occur with different addresses and derivation paths.
Luckily, they have posted the derivation paths for Bitcoin and plenty of altcoins on their GitHub page. Let's just hope it's all correct and there haven't been any changes they failed to make in the below source.
https://github.com/trustwallet/wallet-core/blob/master/registry.json#L9They do have a github account and there are some unrelated code there and a regular user is not capable of figure out that it is actually closed source so they "trust" the wallet easier.
Trust Wallet used to be open-source in the past. But that changed a few years ago.
o_e_l_e_o talked about it here: