Imho, there are 3 possible problems any ACC school considering adding DI men's lacrosse must overcome:

1. Costs;

2. Title IX considerations; and

3. Forming a competitive program.

Thing is, even if you have 1 and 2 under control, there's still 3 to deal with. Imho, if any one ACC program upgrades by itself, it will take several years before that program wins a conference game. For that reason, if you see any ACC expansion, it will likely entail two or more programs upgrading simultaneously.

#1 - Athletic Dept in the black due primarily to YUM Center deal. Plus they already have a fairly new stadium and facility.

#2 - Don't know their Title IX situation and they already have an ACC Women's lacrosse team. Not sure what women's sports they could add, but currently ND HAS 3 men's sports that UofL doesn't have (hockey, M lacrosse, fencing) so you would think they could make room - but I just don't know

EDIT: Quick look at sports offered ND vs UofL:
ND has 3 Men's sports that UofL doesn't have
Fencing
Hockey
Lacrosee
ND and UofL have the same number of woman's sports:
ND has Fencing, UofL doesn't
but UofL has Field Hockey, ND doesn't

Just by the number of sports offered, it would appear that Louisville should have room to add lacrosse under Title IX

By my count, ND is offering 35.1 more men's scholarships than UofL
UofL is offering 7 more women's scholarships than ND.
Assuming ND is in Title IX compliance, then Louisville should have 28.1 scholarships available to men (35.1 - 7 = 28.1)

#3 - As I mentioned above, their club team has been winning conference championships. The area is becoming a new hotbed for lacrosse and there is already a Div I lacrosse team in the city with Bellarmine