The picture here is serious. Three felony drug charges in six months, all while out on bond, is a pattern that courts and prosecutors view as evidence that neither the charges nor the bond conditions have made any impression. Getting arrested for new charges while already released pending trial on separate charges is one of the worst positions a defendant can be in. Bond revocation on both existing cases is almost certain at this point.
Whether habitual offender statutes apply and what sentencing range he faces depends on the specific state and how the prior charges have been adjudicated. Three meth arrests do not automatically mean three convictions, but if prior cases resulted in convictions or guilty pleas, the cumulative weight of a third offense with pending open cases is significant. In states with habitual offender provisions, the exposure can escalate dramatically.
The harder truth is that this situation reflects an addiction that has not been addressed, and the legal system has now exhausted most of its patience with lighter consequences. What comes next is likely serious jail or prison time. The most productive thing that can happen at this point is that treatment becomes part of whatever legal resolution he reaches, but getting that requires an attorney who can negotiate it into the outcome.
You can see where this is headed. The question worth sitting with is what, if anything, changes the trajectory after this.