If that trend continues Trump is not going to be able to keep up in ad spending and GOTV infrastructure. Republicans rely on paid canvassers and staff to do ground work whereas Democrats have a bigger base of volunteers. Biden can put a lot of that money towards ads and opening offices while Trump will be paying legal bills and putting up cheap web ads.
I think Trump's hope has to be that Haley dropping out loosens some big donor wallets who had been holding out hope that he wouldn't be the nominee. Remember Haley dropped out on March 6th so the primary was still ongoing in this period. If the NEXT report doesn't have a big Trump's the Nominee surge this is real trouble.
I actually am starting to see the reason why Biden's toying with spending in Florida and Texas even though I think there's close to zero chance he wins either: if he can force the cash-strapped Trump campaign to spend there that's a huge benefit and when you have a three to one cash edge you can do things like make plays in places purely to force the other side on defense.
