I won't be surprised if you're correct, but the history of the map pack somewhat argues against this.
I've been thinking about what you said.
First let us consider what caused MMP to switch to SK from mounted. I assume that MMP got some leftover stock and possibly got some more printed. There were some marketing advantages "Look they are real mounted, not paper or post card cräp, this is quality!", type of thing, but the relative success of the SK line and the reprint cost and the logistics and shipping (weight) burden of mounted maps clearly must have pushed MMP further towards SK style.
However such a decision would have been fairly drastic, after all, mounted maps were in every core and AP to date and were essential to play all except a few HS/HASL games. In effect every map would have to be replaced, an all or nothing job. It's not as if you could ship BV with 2 mounted and 2 SK maps, depending upon availability. That would not be a cheap switch. In addition, only issuing SK maps in cores (over many years) or via individual map orders (a right pain) would mean players would only get their maps in dribs and drabs. So releasing a map bundle would have seemed like a good "instant catchup" idea and possibly more important, given MMP a cash injection to offset what must have been a big expense. Back then getting it wrong might possibly have ended MMP, not doing anything different could have been a slower but inevitable death.
Overlays are not in the same essential bracket as I don't think even 20% of scenarios use overlays. The release of the like of RS has already dampened the demand for overlays somewhat, the main absence being the DTO ones. While MMP may well make more per overlay package than the same weight of maps, I suspect there is not the same financial urgency. Given then greatly increased output from MMP over the last 5 years or so, I suspect the limitation is drawing/layout time rather than limited finance or strong risk. There might be some lack of enthusiasm, even the most enjoyable of jobs can get a bit of a pain at times, that has to be expected.
So while the map pack history may be, to our pleasant surprise, a good guide, I don't think we should set too much store on that, as both the product is less critical and MMP is in a different state.