1. Record and EP with John Mayer:
What is great about an EP is that it can be experimental in a lot of ways. The music does not need to extended out to a full album. Four or five songs is enough. Even further, it can be recorded in a finite amount of town. Mayer could have McKenna down for a long weekend and they could hash out only what feels right. I particularly want Mayer to be the"elder statesman" because of who he has been playing with lately, The Grateful Dead. As evident in the songs on his latest release "The Search for Everything", Mayer learned from Bob Weir and Company what matters most is whatever makes the best music. The Dead brought in disco, Mayer brings in drum loops and partial pop production, along with his staples of blues and Neil Young arrangements. A cover of "Sugar Magnolia" or "Old Man"would sound fresh and alive with these two.
2. Jam with Arcade Fire:
It could be the result of being the opening act being welcomed onto stage during the main set or McKenna could be a special guest for a couple of nights, either way, I feel he could grow a lot by learning how to fit into a band of that size with such a large crowd on stage. Let him work in playing certain chords to go along with the other guitars. Let him dabble in a little percussion. Let him find himself front and center between Will and Régine and picking up a solo. He could definitely at the least add to the chorus of voices during a cover. Out of the experience, he would be able to enter into indie royalty and learn songs that have aged gracefully.
3. Contribute to a tribute/charity album:
This is a small, simple thing but it can be a lot of fun. Compilations in tribute/celebration to/of Bob Dylan, Buddy Holly, and Paul McCartney have brought together acts from across the spectrum of genres and in particular, some of today's most loved indie darlings. My Morning Jacket, The Black Keys, She & Him, and others have been brought in and put an unique spin on some of rock n roll's greatest songs. What I believe happens is they come to appreciate the art of someone from another time and learn to work into their own songs. Similar to covering the Dead or Neil Young, it would only lead to better Declan McKenna songs.
4. Perform at the Grammys during the tributes:
Once again, he could get himself out there while paying tribute to the greatness of others who have come before him. I can still remember when Foster the People played as part of the honoring of The Beach Boys. It allows for music fans of a different generation to be introduced and become interested in today's talent. Plus it shows how everyone lines up in the lineage. He could assert his place music's family tree.
5. Play with a legend:
This time he would be directly engaging with those who have come before him. He could contribute guitar to a release from Ringo (possibly with McCartney on bass), go on stage with Johnny Marr for "There Is A Light That Never Goes Out", or after playing a set at either the Global Citizen Festival or The Bridge School benefit, being part of the ensemble while "Living in the Free World" or "Twist & Shout" closes things down. Have him quickly look around at those also on stage and be inspired to find himself still there 20, 30, 40 years later.
I know some of these are simple and others are lofty but I believe all of them would make for a long-lasting and once-in-a-lifetime career.