YX also has a crew base in MCI, 9E has a MX base in IND. And RDU has an extensive RJ route network that requires the planes be rotated in somehow.
Yikes forgot about 9E in IND
LGA-MCI, MKE, STL, BNA, IND, RDU are probably next in line. Secondary might be LGA-MSN, OMA, RSW, JAX, EYW, and MAYBE DSM?
From SLC I can see the 220 going on SLC-BUR and LGB.
I don't see those being that important to add, other than RDU, and maybe STL and BNA. LGA-MCI/IND/MKE/e.t.c have weak competition
Secondly, they need to send the RJs somewhere, IND is a big base for YX, BNA is a base for OO, MKE has a mx base for OO, and the other destinations(other than maybe RDU) don't have that much O&D to NYC relatively speaking.
Why would it benefit DL to send a A220 on LGA-MCI/MKE. Both are relatively small destinations for DL, and the only direct competition on those routes would be WN.
They do need to send the 'big' RJs somewhere
, but part of the somewhere is replacing about 60 CR2s worth of capacity between 1/1/19 and 2023. 220s filling in for CR9/E75 creates that capacity. (I'm not arguing for specific routes.)
Capacity is being created elsewhere, for example many routes to MSP and other hubs are going all mainline this summer.
But with regards to LGA/JFK, regardless of upguaging there will always need to be some presence of RJs on routes like IND-NYC, BNA-NYC, e.t.c because of the RJ bases in those areas.
Furthermore, they aren't going to add the A220 somewhere(for now) unless it is an important route strategy wise. Right now the point of the A220 isn't to add long-thin routes, which will come later, the point is to differentiate itself in an important market/route.
Look at SEA-SJC/SFO and DFW-NYC for 3 perfect examples, these are no-doubt important routes in their own right and DL is at a clear disadvantage on these frequency wise. However, the A220 is a clear differentiator against AS and AA respectively. Just look at DFW-LGA, the A220's 2-3 configuration along with PTVs is superior to AA's oasis configured cabins that usually lack PTVs.
Over the next few months I expect to see the A220s announced on more of these highly competitive routes, before the A220s eventually trickle down to the less competitive and/or smaller markets. RDU-LGA screams A220 to me, CLT/ORD-LGA, ORD-BOS, PHX-LAX, and others would fit that bill.