The increased issuance rate is probably the result of PTO's money crunch. Unlike most agencies, which supplement funds appropriate by Congress with collected fees, PTO is expected to be entirely self-supporting. Application fees. Continuation fees. Maintenance fees. Service fees. Everything that PTO does has a dollar sign attached to it (here's the fee schedule). Sometimes they don't even get to keep is all. Congress raided PTO's surplus several times during the boom to prop up the General Treasury. When rainy days came, companies started filing for fewer patents and some - gasp - even let patents lapse rather than paying their maintenance fees. As a result, PTO was forced to cut benefits dramatically. For awhile, overtime was off the table. The agency stopped paying tuition for examiners attending night law programs. Retention bonuses went away. Bad time to be an examiner.
The issuance boost means more continuations, re-applications, etc. along the way to approval = more revenue immediately. More importantly, PTO's got to issue nearly five patents to receive as much by way of maintenance fees in 3-4 years as they WOULD have received from an 11 year old patent that's been allowed to lapse.
Issuance rate won't (and from PTO's perspective, can't) go down unless or until Congress changes PTO's funding model or the economy turns around. Even if the economy gets better, it's going to take a few years for revenues to start increasing as the patents from the current glut start bringing in large maintenance fees and the issuance rate can go down without forcing staff cuts.